diff --git a/server/gameserver/creature.cc b/server/gameserver/creature.cc
index 86848ac8..badca857 100644
--- a/server/gameserver/creature.cc
+++ b/server/gameserver/creature.cc
@@ -1505,11 +1505,12 @@ void Creature::AddInventory(int slot_id, int num)
 
 void Creature::DecInventory(int slot_id, int num)
 {
-    assert(num > 0);
-    if (!IsValidSlotId(slot_id)) {
-        A8_ABORT();
+    if (num > 0) {
+        if (!IsValidSlotId(slot_id)) {
+            A8_ABORT();
+        }
+        inventory_[slot_id].num -= num;
     }
-    inventory_[slot_id].num -= num;
 }
 
 void Creature::CheckSpecObject(int new_poly_flags)