diff --git a/src/libexpr-c/nix_api_expr.cc b/src/libexpr-c/nix_api_expr.cc
index b86d745db..bdf7a1e63 100644
--- a/src/libexpr-c/nix_api_expr.cc
+++ b/src/libexpr-c/nix_api_expr.cc
@@ -42,56 +42,56 @@ nix_err nix_libexpr_init(nix_c_context * context)
 }
 
 nix_err nix_expr_eval_from_string(
-    nix_c_context * context, EvalState * state, const char * expr, const char * path, Value * value)
+    nix_c_context * context, EvalState * state, const char * expr, const char * path, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
         nix::Expr * parsedExpr = state->state.parseExprFromString(expr, state->state.rootPath(nix::CanonPath(path)));
-        state->state.eval(parsedExpr, *(nix::Value *) value);
-        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+        state->state.eval(parsedExpr, value->value);
+        state->state.forceValue(value->value, nix::noPos);
     }
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, Value * arg, Value * value)
+nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, nix_value * arg, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        state->state.callFunction(*(nix::Value *) fn, *(nix::Value *) arg, *(nix::Value *) value, nix::noPos);
-        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+        state->state.callFunction(fn->value, arg->value, value->value, nix::noPos);
+        state->state.forceValue(value->value, nix::noPos);
     }
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_value_call_multi(nix_c_context * context, EvalState * state, Value * fn, size_t nargs, Value ** args, Value * value)
+nix_err nix_value_call_multi(nix_c_context * context, EvalState * state, nix_value * fn, size_t nargs, nix_value ** args, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        state->state.callFunction(*(nix::Value *) fn, nargs, (nix::Value * *)args, *(nix::Value *) value, nix::noPos);
-        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+        state->state.callFunction(fn->value, nargs, (nix::Value * *)args, value->value, nix::noPos);
+        state->state.forceValue(value->value, nix::noPos);
     }
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * value)
+nix_err nix_value_force(nix_c_context * context, EvalState * state, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        state->state.forceValue(*(nix::Value *) value, nix::noPos);
+        state->state.forceValue(value->value, nix::noPos);
     }
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, Value * value)
+nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        state->state.forceValueDeep(*(nix::Value *) value);
+        state->state.forceValueDeep(value->value);
     }
     NIXC_CATCH_ERRS
 }
@@ -181,6 +181,15 @@ nix_err nix_gc_decref(nix_c_context * context, const void *)
 void nix_gc_now() {}
 #endif
 
+nix_err nix_value_incref(nix_c_context * context, nix_value *x)
+{
+    return nix_gc_incref(context, (const void *) x);
+}
+nix_err nix_value_decref(nix_c_context * context, nix_value *x)
+{
+    return nix_gc_decref(context, (const void *) x);
+}
+
 void nix_gc_register_finalizer(void * obj, void * cd, void (*finalizer)(void * obj, void * cd))
 {
 #ifdef HAVE_BOEHMGC
diff --git a/src/libexpr-c/nix_api_expr.h b/src/libexpr-c/nix_api_expr.h
index cb6c00385..adf8b65b1 100644
--- a/src/libexpr-c/nix_api_expr.h
+++ b/src/libexpr-c/nix_api_expr.h
@@ -29,14 +29,23 @@ extern "C" {
  * @see nix_state_create
  */
 typedef struct EvalState EvalState; // nix::EvalState
-/**
- * @brief Represents a value in the Nix language.
+
+/** @brief A Nix language value, or thunk that may evaluate to a value.
+ *
+ * Values are the primary objects manipulated in the Nix language.
+ * They are considered to be immutable from a user's perspective, but the process of evaluating a value changes its
+ * ValueType if it was a thunk. After a value has been evaluated, its ValueType does not change.
+ *
+ * Evaluation in this context refers to the process of evaluating a single value object, also called "forcing" the
+ * value; see `nix_value_force`.
+ *
+ * The evaluator manages its own memory, but your use of the C API must follow the reference counting rules.
  *
- * Owned by the garbage collector.
- * @struct Value
  * @see value_manip
+ * @see nix_value_incref, nix_value_decref
  */
-typedef void Value; // nix::Value
+typedef struct nix_value nix_value;
+[[deprecated("use nix_value instead")]] typedef nix_value Value;
 
 // Function prototypes
 /**
@@ -65,7 +74,7 @@ nix_err nix_libexpr_init(nix_c_context * context);
  * @return NIX_OK if the evaluation was successful, an error code otherwise.
  */
 nix_err nix_expr_eval_from_string(
-    nix_c_context * context, EvalState * state, const char * expr, const char * path, Value * value);
+    nix_c_context * context, EvalState * state, const char * expr, const char * path, nix_value * value);
 
 /**
  * @brief Calls a Nix function with an argument.
@@ -79,7 +88,7 @@ nix_err nix_expr_eval_from_string(
  * @see nix_init_apply() for a similar function that does not performs the call immediately, but stores it as a thunk.
  *      Note the different argument order.
  */
-nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, Value * arg, Value * value);
+nix_err nix_value_call(nix_c_context * context, EvalState * state, nix_value * fn, nix_value * arg, nix_value * value);
 
 /**
  * @brief Calls a Nix function with multiple arguments.
@@ -98,7 +107,7 @@ nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, V
  * @see NIX_VALUE_CALL           For a macro that wraps this function for convenience.
  */
 nix_err nix_value_call_multi(
-    nix_c_context * context, EvalState * state, Value * fn, size_t nargs, Value ** args, Value * value);
+    nix_c_context * context, EvalState * state, nix_value * fn, size_t nargs, nix_value ** args, nix_value * value);
 
 /**
  * @brief Calls a Nix function with multiple arguments.
@@ -116,7 +125,7 @@ nix_err nix_value_call_multi(
  */
 #define NIX_VALUE_CALL(context, state, value, fn, ...)                      \
     do {                                                                    \
-        Value * args_array[] = {__VA_ARGS__};                               \
+        nix_value * args_array[] = {__VA_ARGS__};                           \
         size_t nargs = sizeof(args_array) / sizeof(args_array[0]);          \
         nix_value_call_multi(context, state, fn, nargs, args_array, value); \
     } while (0)
@@ -124,12 +133,10 @@ nix_err nix_value_call_multi(
 /**
  * @brief Forces the evaluation of a Nix value.
  *
- * The Nix interpreter is lazy, and not-yet-evaluated Values can be
+ * The Nix interpreter is lazy, and not-yet-evaluated values can be
  * of type NIX_TYPE_THUNK instead of their actual value.
  *
- * This function converts these Values into their final type.
- *
- * @note This function is mainly needed before calling @ref getters, but not for API calls that return a `Value`.
+ * This function mutates such a `nix_value`, so that, if successful, it has its final type.
  *
  * @param[out] context Optional, stores error information
  * @param[in] state The state of the evaluation.
@@ -138,7 +145,7 @@ nix_err nix_value_call_multi(
  * @return NIX_OK if the force operation was successful, an error code
  * otherwise.
  */
-nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * value);
+nix_err nix_value_force(nix_c_context * context, EvalState * state, nix_value * value);
 
 /**
  * @brief Forces the deep evaluation of a Nix value.
@@ -154,7 +161,7 @@ nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * valu
  * @return NIX_OK if the deep force operation was successful, an error code
  * otherwise.
  */
-nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, Value * value);
+nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, nix_value * value);
 
 /**
  * @brief Create a new Nix language evaluator state.
@@ -188,6 +195,11 @@ void nix_state_free(EvalState * state);
  * you're done with a value returned by the evaluator.
  * @{
  */
+
+// TODO: Deprecate nix_gc_incref in favor of the type-specific reference counting functions?
+//       e.g. nix_value_incref.
+//       It gives implementors more flexibility, and adds safety, so that generated
+//       bindings can be used without fighting the host type system (where applicable).
 /**
  * @brief Increment the garbage collector reference counter for the given object.
  *
diff --git a/src/libexpr-c/nix_api_expr_internal.h b/src/libexpr-c/nix_api_expr_internal.h
index 7743849fd..5a875ef39 100644
--- a/src/libexpr-c/nix_api_expr_internal.h
+++ b/src/libexpr-c/nix_api_expr_internal.h
@@ -20,6 +20,11 @@ struct ListBuilder
     nix::ListBuilder builder;
 };
 
+struct nix_value
+{
+    nix::Value value;
+};
+
 struct nix_string_return
 {
     std::string str;
diff --git a/src/libexpr-c/nix_api_value.cc b/src/libexpr-c/nix_api_value.cc
index 978cf7f43..2f2f99617 100644
--- a/src/libexpr-c/nix_api_value.cc
+++ b/src/libexpr-c/nix_api_value.cc
@@ -21,49 +21,54 @@
 #endif
 
 // Internal helper functions to check [in] and [out] `Value *` parameters
-static const nix::Value & check_value_not_null(const Value * value)
+static const nix::Value & check_value_not_null(const nix_value * value)
 {
     if (!value) {
-        throw std::runtime_error("Value is null");
+        throw std::runtime_error("nix_value is null");
     }
     return *((const nix::Value *) value);
 }
 
-static nix::Value & check_value_not_null(Value * value)
+static nix::Value & check_value_not_null(nix_value * value)
 {
     if (!value) {
-        throw std::runtime_error("Value is null");
+        throw std::runtime_error("nix_value is null");
     }
-    return *((nix::Value *) value);
+    return value->value;
 }
 
-static const nix::Value & check_value_in(const Value * value)
+static const nix::Value & check_value_in(const nix_value * value)
 {
     auto & v = check_value_not_null(value);
     if (!v.isValid()) {
-        throw std::runtime_error("Uninitialized Value");
+        throw std::runtime_error("Uninitialized nix_value");
     }
     return v;
 }
 
-static nix::Value & check_value_in(Value * value)
+static nix::Value & check_value_in(nix_value * value)
 {
     auto & v = check_value_not_null(value);
     if (!v.isValid()) {
-        throw std::runtime_error("Uninitialized Value");
+        throw std::runtime_error("Uninitialized nix_value");
     }
     return v;
 }
 
-static nix::Value & check_value_out(Value * value)
+static nix::Value & check_value_out(nix_value * value)
 {
     auto & v = check_value_not_null(value);
     if (v.isValid()) {
-        throw std::runtime_error("Value already initialized. Variables are immutable");
+        throw std::runtime_error("nix_value already initialized. Variables are immutable");
     }
     return v;
 }
 
+static inline nix_value * as_nix_value_ptr(nix::Value * v)
+{
+    return reinterpret_cast<nix_value *>(v);
+}
+
 /**
  * Helper function to convert calls from nix into C API.
  *
@@ -87,7 +92,7 @@ static void nix_c_primop_wrapper(
     // or maybe something to make blackholes work better; we don't know).
     nix::Value vTmp;
 
-    f(userdata, &ctx, (EvalState *) &state, (Value **) args, (Value *) &vTmp);
+    f(userdata, &ctx, (EvalState *) &state, (nix_value **) args, (nix_value *) &vTmp);
 
     if (ctx.last_err_code != NIX_OK) {
         /* TODO: Throw different errors depending on the error code */
@@ -154,19 +159,19 @@ nix_err nix_register_primop(nix_c_context * context, PrimOp * primOp)
     NIXC_CATCH_ERRS
 }
 
-Value * nix_alloc_value(nix_c_context * context, EvalState * state)
+nix_value * nix_alloc_value(nix_c_context * context, EvalState * state)
 {
     if (context)
         context->last_err_code = NIX_OK;
     try {
-        Value * res = state->state.allocValue();
+        nix_value * res = as_nix_value_ptr(state->state.allocValue());
         nix_gc_incref(nullptr, res);
         return res;
     }
     NIXC_CATCH_ERRS_NULL
 }
 
-ValueType nix_get_type(nix_c_context * context, const Value * value)
+ValueType nix_get_type(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -202,7 +207,7 @@ ValueType nix_get_type(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(NIX_TYPE_NULL);
 }
 
-const char * nix_get_typename(nix_c_context * context, const Value * value)
+const char * nix_get_typename(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -214,7 +219,7 @@ const char * nix_get_typename(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_NULL
 }
 
-bool nix_get_bool(nix_c_context * context, const Value * value)
+bool nix_get_bool(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -226,7 +231,8 @@ bool nix_get_bool(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(false);
 }
 
-nix_err nix_get_string(nix_c_context * context, const Value * value, nix_get_string_callback callback, void * user_data)
+nix_err
+nix_get_string(nix_c_context * context, const nix_value * value, nix_get_string_callback callback, void * user_data)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -238,7 +244,7 @@ nix_err nix_get_string(nix_c_context * context, const Value * value, nix_get_str
     NIXC_CATCH_ERRS
 }
 
-const char * nix_get_path_string(nix_c_context * context, const Value * value)
+const char * nix_get_path_string(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -257,7 +263,7 @@ const char * nix_get_path_string(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_NULL
 }
 
-unsigned int nix_get_list_size(nix_c_context * context, const Value * value)
+unsigned int nix_get_list_size(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -269,7 +275,7 @@ unsigned int nix_get_list_size(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(0);
 }
 
-unsigned int nix_get_attrs_size(nix_c_context * context, const Value * value)
+unsigned int nix_get_attrs_size(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -281,7 +287,7 @@ unsigned int nix_get_attrs_size(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(0);
 }
 
-double nix_get_float(nix_c_context * context, const Value * value)
+double nix_get_float(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -293,7 +299,7 @@ double nix_get_float(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(0.0);
 }
 
-int64_t nix_get_int(nix_c_context * context, const Value * value)
+int64_t nix_get_int(nix_c_context * context, const nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -305,7 +311,7 @@ int64_t nix_get_int(nix_c_context * context, const Value * value)
     NIXC_CATCH_ERRS_RES(0);
 }
 
-ExternalValue * nix_get_external(nix_c_context * context, Value * value)
+ExternalValue * nix_get_external(nix_c_context * context, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -317,7 +323,7 @@ ExternalValue * nix_get_external(nix_c_context * context, Value * value)
     NIXC_CATCH_ERRS_NULL;
 }
 
-Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int ix)
+nix_value * nix_get_list_byidx(nix_c_context * context, const nix_value * value, EvalState * state, unsigned int ix)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -328,12 +334,12 @@ Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalSta
         nix_gc_incref(nullptr, p);
         if (p != nullptr)
             state->state.forceValue(*p, nix::noPos);
-        return (Value *) p;
+        return as_nix_value_ptr(p);
     }
     NIXC_CATCH_ERRS_NULL
 }
 
-Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name)
+nix_value * nix_get_attr_byname(nix_c_context * context, const nix_value * value, EvalState * state, const char * name)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -345,7 +351,7 @@ Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalSt
         if (attr) {
             nix_gc_incref(nullptr, attr->value);
             state->state.forceValue(*attr->value, nix::noPos);
-            return attr->value;
+            return as_nix_value_ptr(attr->value);
         }
         nix_set_err_msg(context, NIX_ERR_KEY, "missing attribute");
         return nullptr;
@@ -353,7 +359,7 @@ Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalSt
     NIXC_CATCH_ERRS_NULL
 }
 
-bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name)
+bool nix_has_attr_byname(nix_c_context * context, const nix_value * value, EvalState * state, const char * name)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -369,8 +375,8 @@ bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState
     NIXC_CATCH_ERRS_RES(false);
 }
 
-Value *
-nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i, const char ** name)
+nix_value * nix_get_attr_byidx(
+    nix_c_context * context, const nix_value * value, EvalState * state, unsigned int i, const char ** name)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -380,12 +386,13 @@ nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * sta
         *name = ((const std::string &) (state->state.symbols[a.name])).c_str();
         nix_gc_incref(nullptr, a.value);
         state->state.forceValue(*a.value, nix::noPos);
-        return a.value;
+        return as_nix_value_ptr(a.value);
     }
     NIXC_CATCH_ERRS_NULL
 }
 
-const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i)
+const char *
+nix_get_attr_name_byidx(nix_c_context * context, const nix_value * value, EvalState * state, unsigned int i)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -397,7 +404,7 @@ const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * valu
     NIXC_CATCH_ERRS_NULL
 }
 
-nix_err nix_init_bool(nix_c_context * context, Value * value, bool b)
+nix_err nix_init_bool(nix_c_context * context, nix_value * value, bool b)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -409,7 +416,7 @@ nix_err nix_init_bool(nix_c_context * context, Value * value, bool b)
 }
 
 // todo string context
-nix_err nix_init_string(nix_c_context * context, Value * value, const char * str)
+nix_err nix_init_string(nix_c_context * context, nix_value * value, const char * str)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -420,7 +427,7 @@ nix_err nix_init_string(nix_c_context * context, Value * value, const char * str
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * value, const char * str)
+nix_err nix_init_path_string(nix_c_context * context, EvalState * s, nix_value * value, const char * str)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -431,7 +438,7 @@ nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * val
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_float(nix_c_context * context, Value * value, double d)
+nix_err nix_init_float(nix_c_context * context, nix_value * value, double d)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -442,7 +449,7 @@ nix_err nix_init_float(nix_c_context * context, Value * value, double d)
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_int(nix_c_context * context, Value * value, int64_t i)
+nix_err nix_init_int(nix_c_context * context, nix_value * value, int64_t i)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -453,7 +460,7 @@ nix_err nix_init_int(nix_c_context * context, Value * value, int64_t i)
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_null(nix_c_context * context, Value * value)
+nix_err nix_init_null(nix_c_context * context, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -464,7 +471,7 @@ nix_err nix_init_null(nix_c_context * context, Value * value)
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_apply(nix_c_context * context, Value * value, Value * fn, Value * arg)
+nix_err nix_init_apply(nix_c_context * context, nix_value * value, nix_value * fn, nix_value * arg)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -477,7 +484,7 @@ nix_err nix_init_apply(nix_c_context * context, Value * value, Value * fn, Value
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_external(nix_c_context * context, Value * value, ExternalValue * val)
+nix_err nix_init_external(nix_c_context * context, nix_value * value, ExternalValue * val)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -504,7 +511,8 @@ ListBuilder * nix_make_list_builder(nix_c_context * context, EvalState * state,
     NIXC_CATCH_ERRS_NULL
 }
 
-nix_err nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, unsigned int index, Value * value)
+nix_err
+nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, unsigned int index, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -524,7 +532,7 @@ void nix_list_builder_free(ListBuilder * list_builder)
 #endif
 }
 
-nix_err nix_make_list(nix_c_context * context, ListBuilder * list_builder, Value * value)
+nix_err nix_make_list(nix_c_context * context, ListBuilder * list_builder, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -535,7 +543,7 @@ nix_err nix_make_list(nix_c_context * context, ListBuilder * list_builder, Value
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_init_primop(nix_c_context * context, Value * value, PrimOp * p)
+nix_err nix_init_primop(nix_c_context * context, nix_value * value, PrimOp * p)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -546,7 +554,7 @@ nix_err nix_init_primop(nix_c_context * context, Value * value, PrimOp * p)
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_copy_value(nix_c_context * context, Value * value, const Value * source)
+nix_err nix_copy_value(nix_c_context * context, nix_value * value, const nix_value * source)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -558,7 +566,7 @@ nix_err nix_copy_value(nix_c_context * context, Value * value, const Value * sou
     NIXC_CATCH_ERRS
 }
 
-nix_err nix_make_attrs(nix_c_context * context, Value * value, BindingsBuilder * b)
+nix_err nix_make_attrs(nix_c_context * context, nix_value * value, BindingsBuilder * b)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -584,7 +592,7 @@ BindingsBuilder * nix_make_bindings_builder(nix_c_context * context, EvalState *
     NIXC_CATCH_ERRS_NULL
 }
 
-nix_err nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * bb, const char * name, Value * value)
+nix_err nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * bb, const char * name, nix_value * value)
 {
     if (context)
         context->last_err_code = NIX_OK;
@@ -605,7 +613,7 @@ void nix_bindings_builder_free(BindingsBuilder * bb)
 #endif
 }
 
-nix_realised_string * nix_string_realise(nix_c_context * context, EvalState * state, Value * value, bool isIFD)
+nix_realised_string * nix_string_realise(nix_c_context * context, EvalState * state, nix_value * value, bool isIFD)
 {
     if (context)
         context->last_err_code = NIX_OK;
diff --git a/src/libexpr-c/nix_api_value.h b/src/libexpr-c/nix_api_value.h
index 244860707..044f68c9e 100644
--- a/src/libexpr-c/nix_api_value.h
+++ b/src/libexpr-c/nix_api_value.h
@@ -35,8 +35,11 @@ typedef enum {
 } ValueType;
 
 // forward declarations
-typedef void Value;
+typedef struct nix_value nix_value;
 typedef struct EvalState EvalState;
+
+[[deprecated("use nix_value instead")]] typedef nix_value Value;
+
 // type defs
 /** @brief Stores an under-construction set of bindings
  * @ingroup value_manip
@@ -90,7 +93,8 @@ typedef struct nix_realised_string nix_realised_string;
  * @param[out] ret return value
  * @see nix_alloc_primop, nix_init_primop
  */
-typedef void (*PrimOpFun)(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret);
+typedef void (*PrimOpFun)(
+    void * user_data, nix_c_context * context, EvalState * state, nix_value ** args, nix_value * ret);
 
 /** @brief Allocate a PrimOp
  *
@@ -142,10 +146,29 @@ nix_err nix_register_primop(nix_c_context * context, PrimOp * primOp);
  * @return value, or null in case of errors
  *
  */
-Value * nix_alloc_value(nix_c_context * context, EvalState * state);
+nix_value * nix_alloc_value(nix_c_context * context, EvalState * state);
+
+/**
+ * @brief Increment the garbage collector reference counter for the given `nix_value`.
+ *
+ * The Nix language evaluator C API keeps track of alive objects by reference counting.
+ * When you're done with a refcounted pointer, call nix_value_decref().
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] value The object to keep alive
+ */
+nix_err nix_value_incref(nix_c_context * context, nix_value * value);
+
+/**
+ * @brief Decrement the garbage collector reference counter for the given object
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] value The object to stop referencing
+ */
+nix_err nix_value_decref(nix_c_context * context, nix_value * value);
 
 /** @addtogroup value_manip Manipulating values
- * @brief Functions to inspect and change Nix language values, represented by Value.
+ * @brief Functions to inspect and change Nix language values, represented by nix_value.
  * @{
  */
 /** @anchor getters
@@ -157,7 +180,7 @@ Value * nix_alloc_value(nix_c_context * context, EvalState * state);
  * @param[in] value Nix value to inspect
  * @return type of nix value
  */
-ValueType nix_get_type(nix_c_context * context, const Value * value);
+ValueType nix_get_type(nix_c_context * context, const nix_value * value);
 
 /** @brief Get type name of value as defined in the evaluator
  * @param[out] context Optional, stores error information
@@ -165,14 +188,14 @@ ValueType nix_get_type(nix_c_context * context, const Value * value);
  * @return type name, owned string
  * @todo way to free the result
  */
-const char * nix_get_typename(nix_c_context * context, const Value * value);
+const char * nix_get_typename(nix_c_context * context, const nix_value * value);
 
 /** @brief Get boolean value
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return true or false, error info via context
  */
-bool nix_get_bool(nix_c_context * context, const Value * value);
+bool nix_get_bool(nix_c_context * context, const nix_value * value);
 
 /** @brief Get the raw string
  *
@@ -186,7 +209,7 @@ bool nix_get_bool(nix_c_context * context, const Value * value);
  * @return error code, NIX_OK on success.
  */
 nix_err
-nix_get_string(nix_c_context * context, const Value * value, nix_get_string_callback callback, void * user_data);
+nix_get_string(nix_c_context * context, const nix_value * value, nix_get_string_callback callback, void * user_data);
 
 /** @brief Get path as string
  * @param[out] context Optional, stores error information
@@ -194,42 +217,42 @@ nix_get_string(nix_c_context * context, const Value * value, nix_get_string_call
  * @return string
  * @return NULL in case of error.
  */
-const char * nix_get_path_string(nix_c_context * context, const Value * value);
+const char * nix_get_path_string(nix_c_context * context, const nix_value * value);
 
 /** @brief Get the length of a list
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return length of list, error info via context
  */
-unsigned int nix_get_list_size(nix_c_context * context, const Value * value);
+unsigned int nix_get_list_size(nix_c_context * context, const nix_value * value);
 
 /** @brief Get the element count of an attrset
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return attrset element count, error info via context
  */
-unsigned int nix_get_attrs_size(nix_c_context * context, const Value * value);
+unsigned int nix_get_attrs_size(nix_c_context * context, const nix_value * value);
 
 /** @brief Get float value in 64 bits
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return float contents, error info via context
  */
-double nix_get_float(nix_c_context * context, const Value * value);
+double nix_get_float(nix_c_context * context, const nix_value * value);
 
 /** @brief Get int value
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return int contents, error info via context
  */
-int64_t nix_get_int(nix_c_context * context, const Value * value);
+int64_t nix_get_int(nix_c_context * context, const nix_value * value);
 
 /** @brief Get external reference
  * @param[out] context Optional, stores error information
  * @param[in] value Nix value to inspect
  * @return reference to external, NULL in case of error
  */
-ExternalValue * nix_get_external(nix_c_context * context, Value *);
+ExternalValue * nix_get_external(nix_c_context * context, nix_value *);
 
 /** @brief Get the ix'th element of a list
  *
@@ -240,7 +263,7 @@ ExternalValue * nix_get_external(nix_c_context * context, Value *);
  * @param[in] ix list element to get
  * @return value, NULL in case of errors
  */
-Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int ix);
+nix_value * nix_get_list_byidx(nix_c_context * context, const nix_value * value, EvalState * state, unsigned int ix);
 
 /** @brief Get an attr by name
  *
@@ -251,7 +274,7 @@ Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalSta
  * @param[in] name attribute name
  * @return value, NULL in case of errors
  */
-Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name);
+nix_value * nix_get_attr_byname(nix_c_context * context, const nix_value * value, EvalState * state, const char * name);
 
 /** @brief Check if an attribute name exists on a value
  * @param[out] context Optional, stores error information
@@ -260,7 +283,7 @@ Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalSt
  * @param[in] name attribute name
  * @return value, error info via context
  */
-bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name);
+bool nix_has_attr_byname(nix_c_context * context, const nix_value * value, EvalState * state, const char * name);
 
 /** @brief Get an attribute by index in the sorted bindings
  *
@@ -274,8 +297,8 @@ bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState
  * @param[out] name will store a pointer to the attribute name
  * @return value, NULL in case of errors
  */
-Value *
-nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i, const char ** name);
+nix_value * nix_get_attr_byidx(
+    nix_c_context * context, const nix_value * value, EvalState * state, unsigned int i, const char ** name);
 
 /** @brief Get an attribute name by index in the sorted bindings
  *
@@ -288,7 +311,8 @@ nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * sta
  * @param[in] i attribute index
  * @return name, NULL in case of errors
  */
-const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i);
+const char *
+nix_get_attr_name_byidx(nix_c_context * context, const nix_value * value, EvalState * state, unsigned int i);
 
 /**@}*/
 /** @name Initializers
@@ -305,7 +329,7 @@ const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * valu
  * @param[in] b the boolean value
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_bool(nix_c_context * context, Value * value, bool b);
+nix_err nix_init_bool(nix_c_context * context, nix_value * value, bool b);
 
 /** @brief Set a string
  * @param[out] context Optional, stores error information
@@ -313,7 +337,7 @@ nix_err nix_init_bool(nix_c_context * context, Value * value, bool b);
  * @param[in] str the string, copied
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_string(nix_c_context * context, Value * value, const char * str);
+nix_err nix_init_string(nix_c_context * context, nix_value * value, const char * str);
 
 /** @brief Set a path
  * @param[out] context Optional, stores error information
@@ -321,7 +345,7 @@ nix_err nix_init_string(nix_c_context * context, Value * value, const char * str
  * @param[in] str the path string, copied
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * value, const char * str);
+nix_err nix_init_path_string(nix_c_context * context, EvalState * s, nix_value * value, const char * str);
 
 /** @brief Set a float
  * @param[out] context Optional, stores error information
@@ -329,7 +353,7 @@ nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * val
  * @param[in] d the float, 64-bits
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_float(nix_c_context * context, Value * value, double d);
+nix_err nix_init_float(nix_c_context * context, nix_value * value, double d);
 
 /** @brief Set an int
  * @param[out] context Optional, stores error information
@@ -338,13 +362,13 @@ nix_err nix_init_float(nix_c_context * context, Value * value, double d);
  * @return error code, NIX_OK on success.
  */
 
-nix_err nix_init_int(nix_c_context * context, Value * value, int64_t i);
+nix_err nix_init_int(nix_c_context * context, nix_value * value, int64_t i);
 /** @brief Set null
  * @param[out] context Optional, stores error information
  * @param[out] value Nix value to modify
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_null(nix_c_context * context, Value * value);
+nix_err nix_init_null(nix_c_context * context, nix_value * value);
 
 /** @brief Set the value to a thunk that will perform a function application when needed.
  *
@@ -360,7 +384,7 @@ nix_err nix_init_null(nix_c_context * context, Value * value);
  * @see nix_value_call() for a similar function that performs the call immediately and only stores the return value.
  *      Note the different argument order.
  */
-nix_err nix_init_apply(nix_c_context * context, Value * value, Value * fn, Value * arg);
+nix_err nix_init_apply(nix_c_context * context, nix_value * value, nix_value * fn, nix_value * arg);
 
 /** @brief Set an external value
  * @param[out] context Optional, stores error information
@@ -368,7 +392,7 @@ nix_err nix_init_apply(nix_c_context * context, Value * value, Value * fn, Value
  * @param[in] val the external value to set. Will be GC-referenced by the value.
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_external(nix_c_context * context, Value * value, ExternalValue * val);
+nix_err nix_init_external(nix_c_context * context, nix_value * value, ExternalValue * val);
 
 /** @brief Create a list from a list builder
  * @param[out] context Optional, stores error information
@@ -376,7 +400,7 @@ nix_err nix_init_external(nix_c_context * context, Value * value, ExternalValue
  * @param[out] value Nix value to modify
  * @return error code, NIX_OK on success.
  */
-nix_err nix_make_list(nix_c_context * context, ListBuilder * list_builder, Value * value);
+nix_err nix_make_list(nix_c_context * context, ListBuilder * list_builder, nix_value * value);
 
 /** @brief Create a list builder
  * @param[out] context Optional, stores error information
@@ -393,7 +417,8 @@ ListBuilder * nix_make_list_builder(nix_c_context * context, EvalState * state,
  * @param[in] value value to insert
  * @return error code, NIX_OK on success.
  */
-nix_err nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, unsigned int index, Value * value);
+nix_err
+nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, unsigned int index, nix_value * value);
 
 /** @brief Free a list builder
  *
@@ -408,7 +433,7 @@ void nix_list_builder_free(ListBuilder * list_builder);
  * @param[in] b bindings builder to use. Make sure to unref this afterwards.
  * @return error code, NIX_OK on success.
  */
-nix_err nix_make_attrs(nix_c_context * context, Value * value, BindingsBuilder * b);
+nix_err nix_make_attrs(nix_c_context * context, nix_value * value, BindingsBuilder * b);
 
 /** @brief Set primop
  * @param[out] context Optional, stores error information
@@ -417,14 +442,14 @@ nix_err nix_make_attrs(nix_c_context * context, Value * value, BindingsBuilder *
  * @see nix_alloc_primop
  * @return error code, NIX_OK on success.
  */
-nix_err nix_init_primop(nix_c_context * context, Value * value, PrimOp * op);
+nix_err nix_init_primop(nix_c_context * context, nix_value * value, PrimOp * op);
 /** @brief Copy from another value
  * @param[out] context Optional, stores error information
  * @param[out] value Nix value to modify
  * @param[in] source value to copy from
  * @return error code, NIX_OK on success.
  */
-nix_err nix_copy_value(nix_c_context * context, Value * value, const Value * source);
+nix_err nix_copy_value(nix_c_context * context, nix_value * value, const nix_value * source);
 /**@}*/
 
 /** @brief Create a bindings builder
@@ -444,7 +469,7 @@ BindingsBuilder * nix_make_bindings_builder(nix_c_context * context, EvalState *
  * @return error code, NIX_OK on success.
  */
 nix_err
-nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * builder, const char * name, Value * value);
+nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * builder, const char * name, nix_value * value);
 
 /** @brief Free a bindings builder
  *
@@ -471,7 +496,7 @@ void nix_bindings_builder_free(BindingsBuilder * builder);
                     You should set this to false when building for your application's purpose.
  * @return NULL if failed, are a new nix_realised_string, which must be freed with nix_realised_string_free
  */
-nix_realised_string * nix_string_realise(nix_c_context * context, EvalState * state, Value * value, bool isIFD);
+nix_realised_string * nix_string_realise(nix_c_context * context, EvalState * state, nix_value * value, bool isIFD);
 
 /** @brief Start of the string
  * @param[in] realised_string
diff --git a/tests/unit/libexpr-support/tests/nix_api_expr.hh b/tests/unit/libexpr-support/tests/nix_api_expr.hh
index d1840d034..6ddca0d14 100644
--- a/tests/unit/libexpr-support/tests/nix_api_expr.hh
+++ b/tests/unit/libexpr-support/tests/nix_api_expr.hh
@@ -25,7 +25,7 @@ protected:
     }
 
     EvalState * state;
-    Value * value;
+    nix_value * value;
 };
 
 }
diff --git a/tests/unit/libexpr/nix_api_expr.cc b/tests/unit/libexpr/nix_api_expr.cc
index 92a6a1175..8b97d6923 100644
--- a/tests/unit/libexpr/nix_api_expr.cc
+++ b/tests/unit/libexpr/nix_api_expr.cc
@@ -39,12 +39,12 @@ TEST_F(nix_api_expr_test, nix_expr_eval_drv)
     ASSERT_EQ(NIX_TYPE_ATTRS, nix_get_type(nullptr, value));
 
     EvalState * stateFn = nix_state_create(nullptr, nullptr, store);
-    Value * valueFn = nix_alloc_value(nullptr, state);
+    nix_value * valueFn = nix_alloc_value(nullptr, state);
     nix_expr_eval_from_string(nullptr, stateFn, "builtins.toString", ".", valueFn);
     ASSERT_EQ(NIX_TYPE_FUNCTION, nix_get_type(nullptr, valueFn));
 
     EvalState * stateResult = nix_state_create(nullptr, nullptr, store);
-    Value * valueResult = nix_alloc_value(nullptr, stateResult);
+    nix_value * valueResult = nix_alloc_value(nullptr, stateResult);
     nix_value_call(ctx, stateResult, valueFn, value, valueResult);
     ASSERT_EQ(NIX_TYPE_STRING, nix_get_type(nullptr, valueResult));
 
@@ -70,7 +70,7 @@ TEST_F(nix_api_expr_test, nix_build_drv)
                               })";
     nix_expr_eval_from_string(nullptr, state, expr, ".", value);
 
-    Value * drvPathValue = nix_get_attr_byname(nullptr, value, state, "drvPath");
+    nix_value * drvPathValue = nix_get_attr_byname(nullptr, value, state, "drvPath");
     std::string drvPath;
     nix_get_string(nullptr, drvPathValue, OBSERVE_STRING(drvPath));
 
@@ -84,7 +84,7 @@ TEST_F(nix_api_expr_test, nix_build_drv)
     StorePath * drvStorePath = nix_store_parse_path(ctx, store, drvPath.c_str());
     ASSERT_EQ(true, nix_store_is_valid_path(ctx, store, drvStorePath));
 
-    Value * outPathValue = nix_get_attr_byname(ctx, value, state, "outPath");
+    nix_value * outPathValue = nix_get_attr_byname(ctx, value, state, "outPath");
     std::string outPath;
     nix_get_string(ctx, outPathValue, OBSERVE_STRING(outPath));
 
@@ -193,7 +193,8 @@ TEST_F(nix_api_expr_test, nix_expr_realise_context)
 
 const char * SAMPLE_USER_DATA = "whatever";
 
-static void primop_square(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret)
+static void
+primop_square(void * user_data, nix_c_context * context, EvalState * state, nix_value ** args, nix_value * ret)
 {
     assert(context);
     assert(state);
@@ -207,17 +208,17 @@ TEST_F(nix_api_expr_test, nix_expr_primop)
     PrimOp * primop =
         nix_alloc_primop(ctx, primop_square, 1, "square", nullptr, "square an integer", (void *) SAMPLE_USER_DATA);
     assert_ctx_ok();
-    Value * primopValue = nix_alloc_value(ctx, state);
+    nix_value * primopValue = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_primop(ctx, primopValue, primop);
     assert_ctx_ok();
 
-    Value * three = nix_alloc_value(ctx, state);
+    nix_value * three = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_int(ctx, three, 3);
     assert_ctx_ok();
 
-    Value * result = nix_alloc_value(ctx, state);
+    nix_value * result = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_value_call(ctx, state, primopValue, three, result);
     assert_ctx_ok();
@@ -226,7 +227,8 @@ TEST_F(nix_api_expr_test, nix_expr_primop)
     ASSERT_EQ(9, r);
 }
 
-static void primop_repeat(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret)
+static void
+primop_repeat(void * user_data, nix_c_context * context, EvalState * state, nix_value ** args, nix_value * ret)
 {
     assert(context);
     assert(state);
@@ -255,27 +257,27 @@ TEST_F(nix_api_expr_test, nix_expr_primop_arity_2_multiple_calls)
     PrimOp * primop =
         nix_alloc_primop(ctx, primop_repeat, 2, "repeat", nullptr, "repeat a string", (void *) SAMPLE_USER_DATA);
     assert_ctx_ok();
-    Value * primopValue = nix_alloc_value(ctx, state);
+    nix_value * primopValue = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_primop(ctx, primopValue, primop);
     assert_ctx_ok();
 
-    Value * hello = nix_alloc_value(ctx, state);
+    nix_value * hello = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_string(ctx, hello, "hello");
     assert_ctx_ok();
 
-    Value * three = nix_alloc_value(ctx, state);
+    nix_value * three = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_int(ctx, three, 3);
     assert_ctx_ok();
 
-    Value * partial = nix_alloc_value(ctx, state);
+    nix_value * partial = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_value_call(ctx, state, primopValue, hello, partial);
     assert_ctx_ok();
 
-    Value * result = nix_alloc_value(ctx, state);
+    nix_value * result = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_value_call(ctx, state, partial, three, result);
     assert_ctx_ok();
@@ -290,22 +292,22 @@ TEST_F(nix_api_expr_test, nix_expr_primop_arity_2_single_call)
     PrimOp * primop =
         nix_alloc_primop(ctx, primop_repeat, 2, "repeat", nullptr, "repeat a string", (void *) SAMPLE_USER_DATA);
     assert_ctx_ok();
-    Value * primopValue = nix_alloc_value(ctx, state);
+    nix_value * primopValue = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_primop(ctx, primopValue, primop);
     assert_ctx_ok();
 
-    Value * hello = nix_alloc_value(ctx, state);
+    nix_value * hello = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_string(ctx, hello, "hello");
     assert_ctx_ok();
 
-    Value * three = nix_alloc_value(ctx, state);
+    nix_value * three = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_int(ctx, three, 3);
     assert_ctx_ok();
 
-    Value * result = nix_alloc_value(ctx, state);
+    nix_value * result = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     NIX_VALUE_CALL(ctx, state, result, primopValue, hello, three);
     assert_ctx_ok();
@@ -318,7 +320,7 @@ TEST_F(nix_api_expr_test, nix_expr_primop_arity_2_single_call)
 }
 
 static void
-primop_bad_no_return(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret)
+primop_bad_no_return(void * user_data, nix_c_context * context, EvalState * state, nix_value ** args, nix_value * ret)
 {
 }
 
@@ -327,17 +329,17 @@ TEST_F(nix_api_expr_test, nix_expr_primop_bad_no_return)
     PrimOp * primop =
         nix_alloc_primop(ctx, primop_bad_no_return, 1, "badNoReturn", nullptr, "a broken primop", nullptr);
     assert_ctx_ok();
-    Value * primopValue = nix_alloc_value(ctx, state);
+    nix_value * primopValue = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_primop(ctx, primopValue, primop);
     assert_ctx_ok();
 
-    Value * three = nix_alloc_value(ctx, state);
+    nix_value * three = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_int(ctx, three, 3);
     assert_ctx_ok();
 
-    Value * result = nix_alloc_value(ctx, state);
+    nix_value * result = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_value_call(ctx, state, primopValue, three, result);
     ASSERT_EQ(ctx->last_err_code, NIX_ERR_NIX_ERROR);
@@ -348,8 +350,8 @@ TEST_F(nix_api_expr_test, nix_expr_primop_bad_no_return)
     ASSERT_THAT(ctx->last_err, testing::Optional(testing::HasSubstr("badNoReturn")));
 }
 
-static void
-primop_bad_return_thunk(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret)
+static void primop_bad_return_thunk(
+    void * user_data, nix_c_context * context, EvalState * state, nix_value ** args, nix_value * ret)
 {
     nix_init_apply(context, ret, args[0], args[1]);
 }
@@ -358,22 +360,22 @@ TEST_F(nix_api_expr_test, nix_expr_primop_bad_return_thunk)
     PrimOp * primop =
         nix_alloc_primop(ctx, primop_bad_return_thunk, 2, "badReturnThunk", nullptr, "a broken primop", nullptr);
     assert_ctx_ok();
-    Value * primopValue = nix_alloc_value(ctx, state);
+    nix_value * primopValue = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_primop(ctx, primopValue, primop);
     assert_ctx_ok();
 
-    Value * toString = nix_alloc_value(ctx, state);
+    nix_value * toString = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_expr_eval_from_string(ctx, state, "builtins.toString", ".", toString);
     assert_ctx_ok();
 
-    Value * four = nix_alloc_value(ctx, state);
+    nix_value * four = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     nix_init_int(ctx, four, 4);
     assert_ctx_ok();
 
-    Value * result = nix_alloc_value(ctx, state);
+    nix_value * result = nix_alloc_value(ctx, state);
     assert_ctx_ok();
     NIX_VALUE_CALL(ctx, state, result, primopValue, toString, four);
 
@@ -387,11 +389,11 @@ TEST_F(nix_api_expr_test, nix_expr_primop_bad_return_thunk)
 
 TEST_F(nix_api_expr_test, nix_value_call_multi_no_args)
 {
-    Value * n = nix_alloc_value(ctx, state);
+    nix_value * n = nix_alloc_value(ctx, state);
     nix_init_int(ctx, n, 3);
     assert_ctx_ok();
 
-    Value * r = nix_alloc_value(ctx, state);
+    nix_value * r = nix_alloc_value(ctx, state);
     nix_value_call_multi(ctx, state, n, 0, nullptr, r);
     assert_ctx_ok();
 
diff --git a/tests/unit/libexpr/nix_api_external.cc b/tests/unit/libexpr/nix_api_external.cc
index 2391f8317..81ff285a4 100644
--- a/tests/unit/libexpr/nix_api_external.cc
+++ b/tests/unit/libexpr/nix_api_external.cc
@@ -49,10 +49,10 @@ TEST_F(nix_api_expr_test, nix_expr_eval_external)
     nix_init_external(ctx, value, val);
 
     EvalState * stateResult = nix_state_create(nullptr, nullptr, store);
-    Value * valueResult = nix_alloc_value(nullptr, stateResult);
+    nix_value * valueResult = nix_alloc_value(nullptr, stateResult);
 
     EvalState * stateFn = nix_state_create(nullptr, nullptr, store);
-    Value * valueFn = nix_alloc_value(nullptr, stateFn);
+    nix_value * valueFn = nix_alloc_value(nullptr, stateFn);
 
     nix_expr_eval_from_string(nullptr, state, "builtins.typeOf", ".", valueFn);
 
diff --git a/tests/unit/libexpr/nix_api_value.cc b/tests/unit/libexpr/nix_api_value.cc
index c71593c85..7fc8b4f64 100644
--- a/tests/unit/libexpr/nix_api_value.cc
+++ b/tests/unit/libexpr/nix_api_value.cc
@@ -4,16 +4,26 @@
 #include "nix_api_util_internal.h"
 #include "nix_api_expr.h"
 #include "nix_api_value.h"
+#include "nix_api_expr_internal.h"
 
 #include "tests/nix_api_expr.hh"
 #include "tests/string_callback.hh"
 
 #include "gmock/gmock.h"
+#include <cstddef>
 #include <cstdlib>
 #include <gtest/gtest.h>
 
 namespace nixC {
 
+TEST_F(nix_api_expr_test, as_nix_value_ptr)
+{
+    // nix_alloc_value casts nix::Value to nix_value
+    // It should be obvious from the decl that that works, but if it doesn't,
+    // the whole implementation would be utterly broken.
+    ASSERT_EQ(sizeof(nix::Value), sizeof(nix_value));
+}
+
 TEST_F(nix_api_expr_test, nix_value_get_int_invalid)
 {
     ASSERT_EQ(0, nix_get_int(ctx, nullptr));
@@ -138,8 +148,8 @@ TEST_F(nix_api_expr_test, nix_build_and_init_list)
     int size = 10;
     ListBuilder * builder = nix_make_list_builder(ctx, state, size);
 
-    Value * intValue = nix_alloc_value(ctx, state);
-    Value * intValue2 = nix_alloc_value(ctx, state);
+    nix_value * intValue = nix_alloc_value(ctx, state);
+    nix_value * intValue2 = nix_alloc_value(ctx, state);
 
     // `init` and `insert` can be called in any order
     nix_init_int(ctx, intValue, 42);
@@ -194,10 +204,10 @@ TEST_F(nix_api_expr_test, nix_build_and_init_attr)
 
     BindingsBuilder * builder = nix_make_bindings_builder(ctx, state, size);
 
-    Value * intValue = nix_alloc_value(ctx, state);
+    nix_value * intValue = nix_alloc_value(ctx, state);
     nix_init_int(ctx, intValue, 42);
 
-    Value * stringValue = nix_alloc_value(ctx, state);
+    nix_value * stringValue = nix_alloc_value(ctx, state);
     nix_init_string(ctx, stringValue, "foo");
 
     nix_bindings_builder_insert(ctx, builder, "a", intValue);
@@ -207,7 +217,7 @@ TEST_F(nix_api_expr_test, nix_build_and_init_attr)
 
     ASSERT_EQ(2, nix_get_attrs_size(ctx, value));
 
-    Value * out_value = nix_get_attr_byname(ctx, value, state, "a");
+    nix_value * out_value = nix_get_attr_byname(ctx, value, state, "a");
     ASSERT_EQ(42, nix_get_int(ctx, out_value));
     nix_gc_decref(ctx, out_value);
 
@@ -251,10 +261,10 @@ TEST_F(nix_api_expr_test, nix_value_init)
     // two = 2;
     // f = a: a * a;
 
-    Value * two = nix_alloc_value(ctx, state);
+    nix_value * two = nix_alloc_value(ctx, state);
     nix_init_int(ctx, two, 2);
 
-    Value * f = nix_alloc_value(ctx, state);
+    nix_value * f = nix_alloc_value(ctx, state);
     nix_expr_eval_from_string(
         ctx,
         state,
@@ -268,7 +278,7 @@ TEST_F(nix_api_expr_test, nix_value_init)
 
     // r = f two;
 
-    Value * r = nix_alloc_value(ctx, state);
+    nix_value * r = nix_alloc_value(ctx, state);
     nix_init_apply(ctx, r, f, two);
     assert_ctx_ok();
 
@@ -297,11 +307,11 @@ TEST_F(nix_api_expr_test, nix_value_init)
 
 TEST_F(nix_api_expr_test, nix_value_init_apply_error)
 {
-    Value * some_string = nix_alloc_value(ctx, state);
+    nix_value * some_string = nix_alloc_value(ctx, state);
     nix_init_string(ctx, some_string, "some string");
     assert_ctx_ok();
 
-    Value * v = nix_alloc_value(ctx, state);
+    nix_value * v = nix_alloc_value(ctx, state);
     nix_init_apply(ctx, v, some_string, some_string);
     assert_ctx_ok();
 
@@ -326,7 +336,7 @@ TEST_F(nix_api_expr_test, nix_value_init_apply_lazy_arg)
     // r = f e
     // r should not throw an exception, because e is not evaluated
 
-    Value * f = nix_alloc_value(ctx, state);
+    nix_value * f = nix_alloc_value(ctx, state);
     nix_expr_eval_from_string(
         ctx,
         state,
@@ -337,9 +347,9 @@ TEST_F(nix_api_expr_test, nix_value_init_apply_lazy_arg)
         f);
     assert_ctx_ok();
 
-    Value * e = nix_alloc_value(ctx, state);
+    nix_value * e = nix_alloc_value(ctx, state);
     {
-        Value * g = nix_alloc_value(ctx, state);
+        nix_value * g = nix_alloc_value(ctx, state);
         nix_expr_eval_from_string(
             ctx,
             state,
@@ -355,7 +365,7 @@ TEST_F(nix_api_expr_test, nix_value_init_apply_lazy_arg)
         nix_gc_decref(ctx, g);
     }
 
-    Value * r = nix_alloc_value(ctx, state);
+    nix_value * r = nix_alloc_value(ctx, state);
     nix_init_apply(ctx, r, f, e);
     assert_ctx_ok();
 
@@ -367,7 +377,7 @@ TEST_F(nix_api_expr_test, nix_value_init_apply_lazy_arg)
     ASSERT_EQ(1, n);
 
     // nix_get_attr_byname isn't lazy (it could have been) so it will throw the exception
-    Value * foo = nix_get_attr_byname(ctx, r, state, "foo");
+    nix_value * foo = nix_get_attr_byname(ctx, r, state, "foo");
     ASSERT_EQ(nullptr, foo);
     ASSERT_THAT(ctx->last_err.value(), testing::HasSubstr("error message for test case nix_value_init_apply_lazy_arg"));
 
@@ -378,7 +388,7 @@ TEST_F(nix_api_expr_test, nix_value_init_apply_lazy_arg)
 
 TEST_F(nix_api_expr_test, nix_copy_value)
 {
-    Value * source = nix_alloc_value(ctx, state);
+    nix_value * source = nix_alloc_value(ctx, state);
 
     nix_init_int(ctx, source, 42);
     nix_copy_value(ctx, value, source);