diff --git a/pkgs/by-name/st/stargate-libcds/package.nix b/pkgs/by-name/st/stargate-libcds/package.nix
index cf6f94c8295a..42db1ef96a83 100644
--- a/pkgs/by-name/st/stargate-libcds/package.nix
+++ b/pkgs/by-name/st/stargate-libcds/package.nix
@@ -17,7 +17,12 @@ stdenv.mkDerivation (finalAttrs: {
   };
 
   # Fix 'error: unrecognized command line option' in platforms other than x86
-  PLAT_FLAGS = lib.optionalString stdenv.hostPlatform.isx86_64 "-mfpmath=sse -mssse3";
+  env = lib.optionalAttrs stdenv.hostPlatform.isx86_64 {
+    PLAT_FLAGS = toString [
+      "-mfpmath=sse"
+      "-mssse3"
+    ];
+  };
 
   patches = [
     # Remove unnecessary tests (valgrind, coverage)