diff --git a/engines/engine.cpp b/engines/engine.cpp
index 1e4543ea4a5..096e4997dd6 100644
--- a/engines/engine.cpp
+++ b/engines/engine.cpp
@@ -655,7 +655,7 @@ bool Engine::warnUserAboutUnsupportedGame() {
 	return true;
 }
 
-void Engine::errorUnsupportedGame(Common::String &extraMsg) {
+void Engine::errorUnsupportedGame(Common::String extraMsg) {
 	Common::String message = extraMsg.empty() ? _("This game is not supported.") : _("This game is not supported for the following reason:\n\n");
 	message += _(extraMsg);
 	message += "\n\n";
diff --git a/engines/engine.h b/engines/engine.h
index 8d82b592d94..4dc63c1de64 100644
--- a/engines/engine.h
+++ b/engines/engine.h
@@ -432,9 +432,9 @@ public:
 	 * Display an error message to the user that the game is not supported.
 	 *
 	 * @param extraMsg    This will be appended to the default message.
-	 *						
+	 *
 	 */
-	static void errorUnsupportedGame(Common::String &extraMsg);
+	static void errorUnsupportedGame(Common::String extraMsg);
 
 	/**
 	 * Get the total play time.