diff --git a/modules/programs/firefox.nix b/modules/programs/firefox.nix
index 8ce84fcb..d79e06a6 100644
--- a/modules/programs/firefox.nix
+++ b/modules/programs/firefox.nix
@@ -343,7 +343,7 @@ in {
             };
 
             userChrome = mkOption {
-              type = types.lines;
+              type = types.oneOf [ types.lines types.path ];
               default = "";
               description = "Custom Firefox user chrome CSS.";
               example = ''
@@ -362,7 +362,7 @@ in {
             };
 
             userContent = mkOption {
-              type = types.lines;
+              type = types.oneOf [ types.lines types.path ];
               default = "";
               description = "Custom Firefox user content CSS.";
               example = ''
@@ -749,10 +749,16 @@ in {
       "${profilesPath}/${profile.path}/.keep".text = "";
 
       "${profilesPath}/${profile.path}/chrome/userChrome.css" =
-        mkIf (profile.userChrome != "") { text = profile.userChrome; };
+        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 != "") { text = profile.userContent; };
+        mkIf (profile.userContent != "") (let
+          key =
+            if builtins.isString profile.userContent then "text" else "source";
+        in { "${key}" = profile.userContent; });
 
       "${profilesPath}/${profile.path}/user.js" = mkIf (profile.settings != { }
         || profile.extraConfig != "" || profile.bookmarks != [ ]) {