diff --git a/user-modules/browser/firefox/default.nix b/user-modules/browser/firefox/default.nix
index 6b10212..7611f43 100644
--- a/user-modules/browser/firefox/default.nix
+++ b/user-modules/browser/firefox/default.nix
@@ -54,8 +54,7 @@ in
 
         # Theming
         userChrome = readFile (
-          pkgs.substituteAll {
-            src = ./userChrome.css;
+          pkgs.replaceVars ./userChrome.css {
             colors = config.desktop.theming.colorsCSS;
           }
         );