diff --git a/pkgs/misc/themes/numix-gtk-theme/default.nix b/pkgs/misc/themes/numix-gtk-theme/default.nix
index f57c1fba1fc..aef1860961c 100644
--- a/pkgs/misc/themes/numix-gtk-theme/default.nix
+++ b/pkgs/misc/themes/numix-gtk-theme/default.nix
@@ -17,8 +17,8 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ gtk-engine-murrine ];
 
-  installPhase = ''
-    make install DESTDIR="$out"
+  postPatch = ''
+    substituteInPlace Makefile --replace '$(DESTDIR)'/usr $out
   '';
 
   meta = {