diff --git a/pkgs/by-name/fb/fb303/package.nix b/pkgs/by-name/fb/fb303/package.nix
index 0cc8ccd7f6d3..3d3cc2a4f3fc 100644
--- a/pkgs/by-name/fb/fb303/package.nix
+++ b/pkgs/by-name/fb/fb303/package.nix
@@ -25,9 +25,6 @@ stdenv.mkDerivation (finalAttrs: {
   };
 
   nativeBuildInputs = [ cmake ];
-  cmakeFlags = [
-    "-DPYTHON_EXTENSIONS=OFF"
-  ];
 
   buildInputs =
     [
@@ -43,6 +40,10 @@ stdenv.mkDerivation (finalAttrs: {
       (darwinMinVersionHook "11.0")
     ];
 
+  cmakeFlags = [
+    "-DPYTHON_EXTENSIONS=OFF"
+  ];
+
   meta = {
     description = "Base Thrift service and a common set of functionality for querying stats, options, and other information from a service";
     homepage = "https://github.com/facebook/fb303";