diff --git a/engines/tinsel/heapmem.cpp b/engines/tinsel/heapmem.cpp
index 7a0766098b8..a3ffea73dc9 100644
--- a/engines/tinsel/heapmem.cpp
+++ b/engines/tinsel/heapmem.cpp
@@ -454,7 +454,7 @@ void MemoryReAlloc(MEM_NODE *pMemNode, long size) {
 	if (size != pMemNode->size) {
 
 		// make sure memory object is not locked and discarded
-		assert(pMemNode->flags == DWM_LOCKED | DWM_DISCARDED);
+		assert(pMemNode->flags == (DWM_LOCKED | DWM_DISCARDED));
 		assert(pMemNode->size == 0);
 
 		// unlink the mnode from the current heap