diff --git a/pkgs/development/libraries/libgdiplus/default.nix b/pkgs/development/libraries/libgdiplus/default.nix
index 1a690ca7aa1f..54bf091e5ea9 100644
--- a/pkgs/development/libraries/libgdiplus/default.nix
+++ b/pkgs/development/libraries/libgdiplus/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ autoreconfHook pkgconfig ];
 
-  configureFlags = stdenv.lib.optionalString stdenv.cc.isClang "--host=${stdenv.hostPlatform.system}";
+  configureFlags = stdenv.lib.optional stdenv.cc.isClang "--host=${stdenv.hostPlatform.system}";
 
   buildInputs =
     [ glib cairo fontconfig libtiff giflib