diff --git a/pkgs/tools/misc/file/default.nix b/pkgs/tools/misc/file/default.nix
index a06b38c0ec7..9dd3970bbb2 100644
--- a/pkgs/tools/misc/file/default.nix
+++ b/pkgs/tools/misc/file/default.nix
@@ -26,8 +26,7 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
-  makeFlags = if stdenv.hostPlatform.isWindows then "FILE_COMPILE=file"
-              else null;
+  makeFlags = stdenv.lib.optional stdenv.hostPlatform.isWindows "FILE_COMPILE=file";
 
   meta = with stdenv.lib; {
     homepage = https://darwinsys.com/file;