diff --git a/src/video/video_driver.cpp b/src/video/video_driver.cpp
--- a/src/video/video_driver.cpp
+++ b/src/video/video_driver.cpp
@@ -87,7 +87,7 @@ void VideoDriver::StartGameThread()
 		this->is_game_threaded = StartNewThread(&this->game_thread, "ottd:game", &VideoDriver::GameThreadThunk, this);
 	}
 
-	DEBUG(driver, 1, "using %sthread for game-loop", this->is_game_threaded ? "" : "no ");
+	Debug(driver, 1, "using {}thread for game-loop", this->is_game_threaded ? "" : "no ");
 }
 
 void VideoDriver::StopGameThread()