diff --git a/pkgs/by-name/co/cosmic-session/package.nix b/pkgs/by-name/co/cosmic-session/package.nix
index cebd00aff004..2c84a130bd9c 100644
--- a/pkgs/by-name/co/cosmic-session/package.nix
+++ b/pkgs/by-name/co/cosmic-session/package.nix
@@ -51,11 +51,10 @@ rustPlatform.buildRustPackage rec {
     "--set"
     "prefix"
     (placeholder "out")
-    "--set"
-    "xdp_cosmic"
-    xdg-desktop-portal-cosmic
   ];
 
+  env.XDP_COSMIC = lib.getExe xdg-desktop-portal-cosmic;
+
   passthru.providedSessions = [ "cosmic" ];
 
   meta = with lib; {