diff --git a/src/gamedata/resourcefiles/resourcefile.h b/src/gamedata/resourcefiles/resourcefile.h
index a07029e84..5ff10c930 100644
--- a/src/gamedata/resourcefiles/resourcefile.h
+++ b/src/gamedata/resourcefiles/resourcefile.h
@@ -74,7 +74,7 @@ struct FResourceLump
 	int ReleaseCache();
 
 protected:
-	virtual int FillCache() {}
+	virtual int FillCache() { return -1; }
 
 };