diff --git a/leetcode/9.py b/leetcode/9.py
index a23e56e..40cbbbf 100644
--- a/leetcode/9.py
+++ b/leetcode/9.py
@@ -3,6 +3,8 @@
 
 class Solution:
     def isPalindrome(self, x: int) -> bool:
+        if x < 0:
+            return False
         str_x = str(x)
         inv_str_x = str_x[::-1]
         int_inv_str_x = int(inv_str_x)