diff --git a/pkgs/by-name/sp/spice-gtk/package.nix b/pkgs/by-name/sp/spice-gtk/package.nix
index 301162b9c6ab..e3f545627bda 100644
--- a/pkgs/by-name/sp/spice-gtk/package.nix
+++ b/pkgs/by-name/sp/spice-gtk/package.nix
@@ -135,7 +135,7 @@ stdenv.mkDerivation rec {
     wayland-protocols
   ];
 
-  PKG_CONFIG_POLKIT_GOBJECT_1_POLICYDIR = "${placeholder "out"}/share/polkit-1/actions";
+  env.PKG_CONFIG_POLKIT_GOBJECT_1_POLICYDIR = "${placeholder "out"}/share/polkit-1/actions";
 
   mesonFlags = [
     "-Dusb-acl-helper-dir=${placeholder "out"}/bin"