diff --git a/modules/programs/firefox/mkFirefoxModule.nix b/modules/programs/firefox/mkFirefoxModule.nix
index 7cf51777c..e2e9935c7 100644
--- a/modules/programs/firefox/mkFirefoxModule.nix
+++ b/modules/programs/firefox/mkFirefoxModule.nix
@@ -870,7 +870,7 @@ in
           _: profile:
           let
             chromePath =
-              if (lib.isPath profile.userChrome && lib.pathIsDirectory profile.userChrome) then
+              if ((i: lib.isPath i && lib.pathIsDirectory i) profile.userChrome) then
                 "chrome"
               else
                 "chrome/userChrome.css";
diff --git a/tests/modules/programs/firefox/common.nix b/tests/modules/programs/firefox/common.nix
index 23a0a718b..35282c041 100644
--- a/tests/modules/programs/firefox/common.nix
+++ b/tests/modules/programs/firefox/common.nix
@@ -22,6 +22,7 @@ builtins.mapAttrs
     "${name}-profiles-overwrite" = ./profiles/overwrite;
     "${name}-profiles-search" = ./profiles/search;
     "${name}-profiles-settings" = ./profiles/settings;
+    "${name}-profiles-userchrome" = ./profiles/userchrome;
     "${name}-state-version-19_09" = ./state-version-19_09.nix;
     "${name}-profiles-shared-path" = ./profiles/shared-path.nix;
   }
diff --git a/tests/modules/programs/firefox/profiles/userchrome/chrome/userChrome.css b/tests/modules/programs/firefox/profiles/userchrome/chrome/userChrome.css
new file mode 100644
index 000000000..120791fd7
--- /dev/null
+++ b/tests/modules/programs/firefox/profiles/userchrome/chrome/userChrome.css
@@ -0,0 +1,5 @@
+#urlbar {
+  min-width: none !important;
+  border: none !important;
+  outline: none !important;
+}
diff --git a/tests/modules/programs/firefox/profiles/userchrome/default.nix b/tests/modules/programs/firefox/profiles/userchrome/default.nix
new file mode 100644
index 000000000..a0640afd8
--- /dev/null
+++ b/tests/modules/programs/firefox/profiles/userchrome/default.nix
@@ -0,0 +1,62 @@
+modulePath:
+{ config, lib, ... }:
+
+let
+
+  cfg = lib.getAttrFromPath modulePath config;
+
+  firefoxMockOverlay = import ../../setup-firefox-mock-overlay.nix modulePath;
+
+in
+{
+  imports = [ firefoxMockOverlay ];
+
+  config = lib.mkIf config.test.enableBig (
+    lib.setAttrByPath modulePath {
+      enable = true;
+      profiles = {
+        basic.isDefault = true;
+        lines = {
+          id = 1;
+          userChrome = # CSS
+            ''
+              #urlbar {
+                min-width: none !important;
+                border: none !important;
+                outline: none !important;
+              }
+            '';
+        };
+        path = {
+          id = 2;
+          userChrome = ./chrome/userChrome.css;
+        };
+        folder = {
+          id = 3;
+          userChrome = ./chrome;
+        };
+      };
+    }
+    // {
+      nmt.script = ''
+        assertFileRegex \
+          home-path/bin/${cfg.wrappedPackageName} \
+          MOZ_APP_LAUNCHER
+
+        assertDirectoryExists home-files/${cfg.configPath}/basic
+
+        assertFileContent \
+          home-files/${cfg.configPath}/lines/chrome/userChrome.css \
+          ${./expected-userchrome.css}
+
+        assertFileContent \
+          home-files/${cfg.configPath}/path/chrome/userChrome.css \
+          ${./expected-userchrome.css}
+
+        assertFileContent \
+          home-files/${cfg.configPath}/folder/chrome/userChrome.css \
+          ${./expected-userchrome.css}
+      '';
+    }
+  );
+}
diff --git a/tests/modules/programs/firefox/profiles/userchrome/expected-userchrome.css b/tests/modules/programs/firefox/profiles/userchrome/expected-userchrome.css
new file mode 100644
index 000000000..120791fd7
--- /dev/null
+++ b/tests/modules/programs/firefox/profiles/userchrome/expected-userchrome.css
@@ -0,0 +1,5 @@
+#urlbar {
+  min-width: none !important;
+  border: none !important;
+  outline: none !important;
+}