diff --git a/modules/programs/firefox/mkFirefoxModule.nix b/modules/programs/firefox/mkFirefoxModule.nix
index 07df1cf4c..782ced931 100644
--- a/modules/programs/firefox/mkFirefoxModule.nix
+++ b/modules/programs/firefox/mkFirefoxModule.nix
@@ -397,19 +397,12 @@ in
               };
 
               userChrome = mkOption {
-                type = types.nullOr (
-                  types.oneOf [
-                    types.lines
-                    types.path
-                  ]
-                );
-                default = null;
-                description = ''
-                  Custom ${appName} user chrome CSS.
-
-                  This can be a path to a file or directory in the Nix store,
-                  or a derivation, or a verbatim multi-line string.
-                '';
+                type = types.oneOf [
+                  types.lines
+                  types.path
+                ];
+                default = "";
+                description = "Custom ${appName} user chrome CSS.";
                 example = ''
                   /* Hide tab bar in FF Quantum */
                   @-moz-document url(chrome://browser/content/browser.xul), url(chrome://browser/content/browser.xhtml) {
@@ -868,35 +861,21 @@ in
         ]
         ++ lib.flip mapAttrsToList cfg.profiles (
           _: profile:
-          let
-            chromePath =
-              if ((i: (lib.isPath i && lib.pathIsDirectory i) || lib.isDerivation i) profile.userChrome) then
-                "chrome"
-              else
-                "chrome/userChrome.css";
-            sourcePath =
-              if ((i: (lib.isPath i && lib.types.path.check i) || lib.isDerivation i) profile.userChrome) then
-                profile.userChrome
-              else
-                null;
-          in
           # Merge the regular profile settings with extension settings
           mkMerge (
             [
-              (mkIf (profile.userChrome != null) {
-                "${profilesPath}/${profile.path}/${chromePath}" =
-                  if sourcePath == null then
-                    {
-                      text = profile.userChrome;
-                    }
-                  else
-                    {
-                      source = sourcePath;
-                    };
-              })
               {
                 "${profilesPath}/${profile.path}/.keep".text = "";
 
+                "${profilesPath}/${profile.path}/chrome/userChrome.css" = mkIf (profile.userChrome != "") (
+                  let
+                    key = if builtins.isString profile.userChrome then "text" else "source";
+                  in
+                  {
+                    "${key}" = profile.userChrome;
+                  }
+                );
+
                 "${profilesPath}/${profile.path}/chrome/userContent.css" = mkIf (profile.userContent != "") (
                   let
                     key = if builtins.isString profile.userContent then "text" else "source";
diff --git a/tests/modules/programs/firefox/profiles/userchrome/default.nix b/tests/modules/programs/firefox/profiles/userchrome/default.nix
index 02c68219f..91563a472 100644
--- a/tests/modules/programs/firefox/profiles/userchrome/default.nix
+++ b/tests/modules/programs/firefox/profiles/userchrome/default.nix
@@ -1,12 +1,15 @@
 modulePath:
-{ config, lib, ... }:
-
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
 let
 
   cfg = lib.getAttrFromPath modulePath config;
 
   firefoxMockOverlay = import ../../setup-firefox-mock-overlay.nix modulePath;
-
 in
 {
   imports = [ firefoxMockOverlay ];
@@ -18,36 +21,15 @@ in
         basic.isDefault = true;
         lines = {
           id = 1;
-          userChrome = ''
-            /*
-              This is a simple comment that should be written inside the `chrome/userChrome.css`
-            */
-
-            #urlbar {
-              min-width: none !important;
-              border: none !important;
-              outline: none !important;
-            }
-          '';
+          userChrome = builtins.readFile ./chrome/userChrome.css;
         };
-        path = {
+        file = {
           id = 2;
           userChrome = ./chrome/userChrome.css;
         };
-        folder = {
-          id = 3;
-          userChrome = ./chrome;
-        };
-        derivation = {
+        derivation-file = {
           id = 4;
-          userChrome = config.lib.test.mkStubPackage {
-            name = "wavefox";
-            buildScript = ''
-              mkdir -p $out
-              ln -s ${./chrome/userChrome.css} $out/userChrome.css
-              echo test > $out/README.md
-            '';
-          };
+          userChrome = pkgs.writeText "userChrome.css" (builtins.readFile ./chrome/userChrome.css);
         };
       };
     }
@@ -59,28 +41,18 @@ in
 
         assertDirectoryExists home-files/${cfg.configPath}/basic
 
-        assertPathNotExists \
-          home-files/${cfg.configPath}/lines/chrome/extraFile.css
         assertFileContent \
           home-files/${cfg.configPath}/lines/chrome/userChrome.css \
           ${./chrome/userChrome.css}
 
+        assertFileContent \
+          home-files/${cfg.configPath}/file/chrome/userChrome.css \
+          ${./chrome/userChrome.css}
+
         assertPathNotExists \
-          home-files/${cfg.configPath}/path/chrome/extraFile.css
+          home-files/${cfg.configPath}/derivation-file/chrome/extraFile.css
         assertFileContent \
-          home-files/${cfg.configPath}/path/chrome/userChrome.css \
-          ${./chrome/userChrome.css}
-
-        assertFileExists \
-          home-files/${cfg.configPath}/folder/chrome/extraFile.css
-        assertFileContent \
-          home-files/${cfg.configPath}/folder/chrome/userChrome.css \
-          ${./chrome/userChrome.css}
-
-        assertFileExists \
-          home-files/${cfg.configPath}/derivation/chrome/README.md
-        assertFileContent \
-          home-files/${cfg.configPath}/derivation/chrome/userChrome.css \
+          home-files/${cfg.configPath}/derivation-file/chrome/userChrome.css \
           ${./chrome/userChrome.css}
       '';
     }