diff --git a/src/newgrf_generic.cpp b/src/newgrf_generic.cpp
--- a/src/newgrf_generic.cpp
+++ b/src/newgrf_generic.cpp
@@ -139,7 +139,7 @@ void AddGenericCallback(uint8 feature, c
 		}
 	}
 
-	DEBUG(grf, 1, "Unhandled generic feature variable 0x%02X", variable);
+	Debug(grf, 1, "Unhandled generic feature variable 0x{:02X}", variable);
 
 	*available = false;
 	return UINT_MAX;