diff --git a/pkgs/applications/networking/browsers/firefox/wrapper.nix b/pkgs/applications/networking/browsers/firefox/wrapper.nix
index 5976eb00cb86..2083d60b3656 100644
--- a/pkgs/applications/networking/browsers/firefox/wrapper.nix
+++ b/pkgs/applications/networking/browsers/firefox/wrapper.nix
@@ -71,6 +71,7 @@ let
       pkcs11Modules ? [ ],
       useGlvnd ? (!isDarwin),
       cfg ? config.${applicationName} or { },
+      appDataDir ? null,
 
       ## Following options are needed for extra prefs & policies
       # For more information about anti tracking (german website)
@@ -334,6 +335,11 @@ let
         "MOZ_ALLOW_DOWNGRADE"
         "1"
       ]
+      ++ lib.optionals (appDataDir != null) [
+        "--set"
+        "MOZ_APP_DATA"
+        appDataDir
+      ]
       ++ lib.optionals (!isDarwin) [
         "--suffix"
         "GTK_PATH"