diff --git a/Source/monstdat.h b/Source/monstdat.h
index 95a3861f9..b555465d7 100644
--- a/Source/monstdat.h
+++ b/Source/monstdat.h
@@ -55,7 +55,7 @@ enum _mai_id : int8_t {
 	AI_INVALID = -1,
 };
 
-enum class MonsterClass {
+enum class MonsterClass : uint8_t {
 	Undead,
 	Demon,
 	Animal,