diff --git a/src/newgrf_airporttiles.h b/src/newgrf_airporttiles.h
--- a/src/newgrf_airporttiles.h
+++ b/src/newgrf_airporttiles.h
@@ -38,7 +38,7 @@ struct AirportTileScopeResolver : public
 	}
 
 	uint32_t GetRandomBits() const override;
-	uint32_t GetVariable(byte variable, uint32_t parameter, bool *available) const override;
+	uint32_t GetVariable(byte variable, [[maybe_unused]] uint32_t parameter, bool *available) const override;
 };
 
 /** Resolver for tiles of an airport. */