diff --git a/tests/modules/programs/firefox/deprecated-native-messenger.nix b/tests/modules/programs/firefox/deprecated-native-messenger.nix
index 95e9d318..cf5f188b 100644
--- a/tests/modules/programs/firefox/deprecated-native-messenger.nix
+++ b/tests/modules/programs/firefox/deprecated-native-messenger.nix
@@ -13,6 +13,7 @@ with lib;
       (self: super: {
         firefox-unwrapped = pkgs.runCommandLocal "firefox-0" {
           meta.description = "I pretend to be Firefox";
+          passthru.gtk3 = null;
         } ''
           mkdir -p "$out/bin"
           touch "$out/bin/firefox"
diff --git a/tests/modules/programs/firefox/profile-settings.nix b/tests/modules/programs/firefox/profile-settings.nix
index b90fd919..af449868 100644
--- a/tests/modules/programs/firefox/profile-settings.nix
+++ b/tests/modules/programs/firefox/profile-settings.nix
@@ -20,6 +20,7 @@ with lib;
           meta.description = "I pretend to be Firefox";
           preferLocalBuild = true;
           allowSubstitutes = false;
+          passthru.gtk3 = null;
         } ''
           mkdir -p "$out/bin"
           touch "$out/bin/firefox"
diff --git a/tests/modules/programs/firefox/state-version-19_09.nix b/tests/modules/programs/firefox/state-version-19_09.nix
index 27dc867a..82fa039c 100644
--- a/tests/modules/programs/firefox/state-version-19_09.nix
+++ b/tests/modules/programs/firefox/state-version-19_09.nix
@@ -14,6 +14,7 @@ with lib;
           meta.description = "I pretend to be Firefox";
           preferLocalBuild = true;
           allowSubstitutes = false;
+          passthru.gtk3 = null;
         } ''
           mkdir -p "$out/bin"
           touch "$out/bin/firefox"