diff --git a/index.html b/index.html
index 9717bef..712b89b 100644
--- a/index.html
+++ b/index.html
@@ -12,6 +12,9 @@
   }
 
   function divide(a, b) {
+    if(b <= 0) {
+      throw 'b must be greater than0'
+    }
     return a/b;
   }