diff --git a/src/libstore-c/nix_api_store.h b/src/libstore-c/nix_api_store.h
index 1309f99b7..577b70151 100644
--- a/src/libstore-c/nix_api_store.h
+++ b/src/libstore-c/nix_api_store.h
@@ -111,7 +111,9 @@ bool nix_store_is_valid_path(nix_c_context * context, Store * store, StorePath *
 /**
  * @brief Realise a Nix store path
  *
- * Blocking, calls callback once for each realised output
+ * Blocking, calls callback once for each realised output.
+ *
+ * @note When working with expressions, consider using e.g. nix_string_realise to get the output. `.drvPath` may not be accurate or available in the future. See https://github.com/NixOS/nix/issues/6507
  *
  * @param[out] context Optional, stores error information
  * @param[in] store Nix Store reference
diff --git a/tests/unit/libexpr/nix_api_expr.cc b/tests/unit/libexpr/nix_api_expr.cc
index 3808bf0eb..fad078d0c 100644
--- a/tests/unit/libexpr/nix_api_expr.cc
+++ b/tests/unit/libexpr/nix_api_expr.cc
@@ -74,6 +74,9 @@ TEST_F(nix_api_expr_test, nix_build_drv)
     std::string pEnd = "-myname.drv";
     ASSERT_EQ(pEnd, p.substr(p.size() - pEnd.size()));
 
+    // NOTE: .drvPath should be usually be ignored. Output paths are more versatile.
+    //       See https://github.com/NixOS/nix/issues/6507
+    //       Use e.g. nix_string_realise to realise the output.
     StorePath * drvStorePath = nix_store_parse_path(ctx, store, drvPath);
     ASSERT_EQ(true, nix_store_is_valid_path(ctx, store, drvStorePath));
 
@@ -88,11 +91,9 @@ TEST_F(nix_api_expr_test, nix_build_drv)
     StorePath * outStorePath = nix_store_parse_path(ctx, store, outPath);
     ASSERT_EQ(false, nix_store_is_valid_path(ctx, store, outStorePath));
 
-    // TODO figure out why fails.
-    // `make libexpr-tests_RUN` works, but `nix build .` enters an infinite loop
-    /* nix_store_realise(ctx, store, drvStorePath, nullptr, nullptr); */
-    /* auto is_valid_path = nix_store_is_valid_path(ctx, store, outStorePath); */
-    /* ASSERT_EQ(true, is_valid_path); */
+    nix_store_realise(ctx, store, drvStorePath, nullptr, nullptr);
+    auto is_valid_path = nix_store_is_valid_path(ctx, store, outStorePath);
+    ASSERT_EQ(true, is_valid_path);
 
     // Clean up
     nix_store_path_free(drvStorePath);