diff --git a/pkgs/by-name/ps/pspp/package.nix b/pkgs/by-name/ps/pspp/package.nix
index 3ef4dbbe2423..bb720dc07489 100644
--- a/pkgs/by-name/ps/pspp/package.nix
+++ b/pkgs/by-name/ps/pspp/package.nix
@@ -55,9 +55,11 @@ stdenv.mkDerivation rec {
     iconv
   ];
 
-  C_INCLUDE_PATH =
-    "${libxml2.dev}/include/libxml2/:" + lib.makeSearchPathOutput "dev" "include" buildInputs;
-  LIBRARY_PATH = lib.makeLibraryPath buildInputs;
+  env = {
+    C_INCLUDE_PATH =
+      "${libxml2.dev}/include/libxml2/:" + lib.makeSearchPathOutput "dev" "include" buildInputs;
+    LIBRARY_PATH = lib.makeLibraryPath buildInputs;
+  };
 
   doCheck = false;