diff --git a/src/entity/item/tool.rs b/src/entity/item/tool.rs
index a5a6645..cd9029b 100644
--- a/src/entity/item/tool.rs
+++ b/src/entity/item/tool.rs
@@ -218,7 +218,7 @@ impl ToolType {
         }
     }
 
-    pub fn max_stack(&self) -> u8 {
+    pub fn max_stack(&self) -> usize {
         match self {
             ToolType::Monomate => 10,
             ToolType::Dimate => 10,