diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 59ab1f874..a32c4a24b 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -99,6 +99,8 @@ EvalCommand::EvalCommand()
 // extern std::function<void(const Error & error, const std::map<std::string, Value *> & env)> debuggerHook;
 extern std::function<void(const Error & error, const Env & env)> debuggerHook;
 
+
+
 ref<EvalState> EvalCommand::getEvalState()
 {
     std::cout << " EvalCommand::getEvalState()" << startReplOnEvalErrors << std::endl;
@@ -107,7 +109,8 @@ ref<EvalState> EvalCommand::getEvalState()
         if (startReplOnEvalErrors)
             debuggerHook = [evalState{ref<EvalState>(evalState)}](const Error & error, const Env & env) {
                 printError("%s\n\n" ANSI_BOLD "Starting REPL to allow you to inspect the current state of the evaluator.\n" ANSI_NORMAL, error.what());
-                runRepl(evalState, env);
+                auto vm = mapEnvBindings(env);
+                runRepl(evalState, *vm);
             };
     }
     return ref<EvalState>(evalState);
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index eef4974e5..2e885bb7c 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -668,6 +668,28 @@ LocalNoInline(void addBindings(string prefix, Bindings &b, valmap &valmap))
     }
 }
 
+
+
+void mapEnvBindings(const Env &env, valmap & vm)
+{
+  // add bindings for the next level up first.
+  if (env.up) {
+    mapEnvBindings(*env.up, vm);
+  }
+
+  // merge - and write over - higher level bindings.
+  vm.merge(*env.valuemap);
+}
+
+valmap * mapEnvBindings(const Env &env)
+{
+    auto vm = new valmap();
+
+    mapEnvBindings(env, *vm);
+
+    return vm;
+}
+
 // LocalNoInline(valmap * mapEnvBindings(Env &env))
 // {
 //     // NOT going to use this
@@ -1508,8 +1530,8 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
         /* For each formal argument, get the actual argument.  If
            there is no matching actual argument but the formal
            argument has a default, use the default. */
+        size_t attrsUsed = 0;
         if (debuggerHook) {
-            size_t attrsUsed = 0;
             for (auto & i : lambda.formals->formals) {
                 Bindings::iterator j = arg.attrs->find(i.name);
                 if (j == arg.attrs->end()) {
@@ -1531,7 +1553,6 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
         else {
             auto map = new valmap();
             
-            size_t attrsUsed = 0;
             for (auto & i : lambda.formals->formals) {
                 Bindings::iterator j = arg.attrs->find(i.name);
                 if (j == arg.attrs->end()) {
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 448f41def..2d167e6eb 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -44,6 +44,7 @@ struct Env
     Value * values[0];
 };
 
+valmap * mapEnvBindings(const Env &env);
 
 Value & mkString(Value & v, std::string_view s, const PathSet & context = PathSet());