diff --git a/pkgs/applications/window-managers/bspwm/default.nix b/pkgs/applications/window-managers/bspwm/default.nix
index dc9d2f35965a..83e1ea3e88d2 100644
--- a/pkgs/applications/window-managers/bspwm/default.nix
+++ b/pkgs/applications/window-managers/bspwm/default.nix
@@ -15,7 +15,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ libxcb libXinerama xcbutil xcbutilkeysyms xcbutilwm ];
 
-  PREFIX = "$out";
+  makeFlags = [ "PREFIX=$(out)" ];
 
   meta = with stdenv.lib; {
     description = "A tiling window manager based on binary space partitioning";