diff --git a/src/game/engine/tests/unit/test_credits_screen.gd b/src/game/engine/tests/unit/test_credits_screen.gd
index 71ed1046..fb51c85e 100644
--- a/src/game/engine/tests/unit/test_credits_screen.gd
+++ b/src/game/engine/tests/unit/test_credits_screen.gd
@@ -7,6 +7,13 @@ const CreditsScript: GDScript = preload("res://engine/scenes/menus/credits.gd")
 const CREDITS_PATH: String = "res://public/games/age-of-dwarves/data/credits.json"
 
 
+func before_all() -> void:
+	# ThemeVocabulary is an autoload; in headless GUT the theme is never
+	# loaded by anyone else, so has_key/lookup return defaults until we
+	# call this. Mirrors what main_menu.gd does at runtime.
+	ThemeVocabulary.load_vocabulary("age-of-dwarves")
+
+
 func test_credits_json_exists_and_is_valid() -> void:
 	assert_true(FileAccess.file_exists(CREDITS_PATH),
 			"credits.json must live at the canonical game-pack path")