diff --git a/pkgs/servers/sql/postgresql/9.4.x.nix b/pkgs/servers/sql/postgresql/9.4.x.nix
index d09a6528222..0309b9b5435 100644
--- a/pkgs/servers/sql/postgresql/9.4.x.nix
+++ b/pkgs/servers/sql/postgresql/9.4.x.nix
@@ -31,6 +31,14 @@ stdenv.mkDerivation rec {
 
   LC_ALL = "C";
 
+  postInstall =
+    ''
+      # Prevent a retained dependency on gcc-wrapper.
+      substituteInPlace $out/lib/pgxs/src/Makefile.global --replace ${stdenv.cc}/bin/ld ld
+    '';
+
+  disallowedReferences = [ stdenv.cc ];
+
   passthru = {
     inherit readline;
     psqlSchema = "9.4";