--- core/src/DecodeHints.h
+++ core/src/DecodeHints.h
@@ -167,7 +167,7 @@
 		FLAG_COUNT
 	};
 
-	static_assert(FLAG_COUNT < 8 * sizeof(_flags), "HintFlag overflow");
+	static_assert(FLAG_COUNT < 8 * sizeof(decltype(_flags)), "HintFlag overflow");
 
 	bool getFlag(int f) const {
 		return (_flags & (1 << f)) != 0;
