diff --git a/src/features/product/ui/Product.tsx b/src/features/product/ui/Product.tsx
index 925e082..01c9224 100644
--- a/src/features/product/ui/Product.tsx
+++ b/src/features/product/ui/Product.tsx
@@ -199,12 +199,12 @@ const ProductDetail = () => {
 
   const handleDecrease = () => {
     setQuantity((q) => {
-      const base = q === '' || q === '.' || q === ',' ? 0 : Number(q);
+      const base = q === '' || q === '.' || q === ',' ? MIN_QTY : Number(q);
       let next = base - STEP;
 
       if (isGram) next = Math.floor(next / STEP) * STEP;
 
-      return next <= MIN_QTY ? MIN_QTY : next;
+      return Math.max(next, MIN_QTY);
     });
   };
 
@@ -256,7 +256,8 @@ const ProductDetail = () => {
             <div className="flex items-center gap-4">
               <button
                 onClick={handleDecrease}
-                className="p-2 border rounded hover:bg-gray-50"
+                disabled={numericQty <= MIN_QTY}
+                className="p-2 border rounded hover:bg-gray-50 disabled:opacity-40 disabled:cursor-not-allowed"
               >
                 <Minus />
               </button>