diff --git a/pkgs/development/libraries/db/generic.nix b/pkgs/development/libraries/db/generic.nix
index bbfd5820ffc5..50695b6349db 100644
--- a/pkgs/development/libraries/db/generic.nix
+++ b/pkgs/development/libraries/db/generic.nix
@@ -83,7 +83,7 @@ stdenv.mkDerivation (
       popd
     '';
 
-    NIX_CFLAGS_COMPILE = [
+    env.NIX_CFLAGS_COMPILE = toString [
       "-Wno-error=incompatible-pointer-types"
     ];