diff --git a/storage/chest.lua b/storage/chest.lua
index c3c6c1b..cc2836d 100644
--- a/storage/chest.lua
+++ b/storage/chest.lua
@@ -65,7 +65,7 @@ function Chest:toSerializable()
     local stackSer = v:toSerializable()
 
     -- Skip all but the first homogeneous slot
-    if stackSer:isEmpty() then
+    if v:isEmpty() then
         if skipEmpty then
             goto continue
         end