diff --git a/coal-crafter.lua b/coal-crafter.lua
index c80cb98..19bd284 100644
--- a/coal-crafter.lua
+++ b/coal-crafter.lua
@@ -8,14 +8,24 @@ local MIN_ESSENCE_NEEDED = 8
 local COAL_ESSENCE_NAME = 'mysticalagriculture:coal_essence'
 local COAL_NAME = 'minecraft:coal'
 
+local function countCoalItems(inventory)
+  local total = 0
+
+  for slot, item in pairs(inventory.list()) do
+    if item.name == COAL_NAME then
+      total = total + item.count
+    end
+  end
+
+  return total
+end
+
 local function waitForNotEnoughCoal(inventory)
   while true do
-    for slot, item in pairs(inventory.list()) do
-      local enoughCoal = item.name == COAL_NAME and item.count >= NB_NEEDED_COAL
+    local nbCoals = countCoalItems(inventory)
 
-      if not enoughCoal then
-        return
-      end
+    if nbCoals < NB_NEEDED_COAL then
+      return
     end
 
     os.sleep(IDLE_TIME_ENOUGH_COAL)