diff --git a/common/hashmap.h b/common/hashmap.h
index 70e7550b8ee..70f00d9930f 100644
--- a/common/hashmap.h
+++ b/common/hashmap.h
@@ -451,7 +451,7 @@ template<class Key, class Val, class HashFunc, class EqualFunc>
 void HashMap<Key, Val, HashFunc, EqualFunc>::expandStorage(size_type newCapacity) {
 	assert(newCapacity > _mask + 1);
 
-#ifndef NDEBUG
+#ifndef RELEASE_BUILD
 	const size_type old_size = _size;
 #endif
 	const size_type old_mask = _mask;
@@ -484,9 +484,11 @@ void HashMap<Key, Val, HashFunc, EqualFunc>::expandStorage(size_type newCapacity
 		_size++;
 	}
 
+#ifndef RELEASE_BUILD
 	// Perform a sanity check: Old number of elements should match the new one!
 	// This check will fail if some previous operation corrupted this hashmap.
 	assert(_size == old_size);
+#endif
 
 	delete[] old_storage;