diff --git a/arrays_strings/str_diff/str_diff_solution.ipynb b/arrays_strings/str_diff/str_diff_solution.ipynb
index 48efa0c7..c8ee4458 100644
--- a/arrays_strings/str_diff/str_diff_solution.ipynb
+++ b/arrays_strings/str_diff/str_diff_solution.ipynb
@@ -115,7 +115,7 @@
     "            if seen[char] < 0:\n",
     "                return char\n",
     "        for char, count in seen.items():\n",
-    "            return char\n",
+    "            if (count == 1): return char\n",
     "\n",
     "    def find_diff_xor(self, str1, str2):\n",
     "        if str1 is None or str2 is None:\n",
@@ -160,6 +160,7 @@
     "        self.assertRaises(TypeError, solution.find_diff, None)\n",
     "        self.assertEqual(solution.find_diff('ab', 'aab'), 'a')\n",
     "        self.assertEqual(solution.find_diff('aab', 'ab'), 'a')\n",
+    "        self.assertEqual(solution.find_diff('baa', 'ab'), 'a')\n",
     "        self.assertEqual(solution.find_diff('abcd', 'abcde'), 'e')\n",
     "        self.assertEqual(solution.find_diff('aaabbcdd', 'abdbacade'), 'e')\n",
     "        self.assertEqual(solution.find_diff_xor('ab', 'aab'), 'a')\n",
@@ -212,9 +213,9 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.7.2"
+   "version": "3.7.6"
   }
  },
  "nbformat": 4,
  "nbformat_minor": 1
-}
+}
\ No newline at end of file
diff --git a/arrays_strings/str_diff/test_str_diff.py b/arrays_strings/str_diff/test_str_diff.py
index 0ff4c95b..79638db0 100644
--- a/arrays_strings/str_diff/test_str_diff.py
+++ b/arrays_strings/str_diff/test_str_diff.py
@@ -8,6 +8,7 @@ def test_find_diff(self):
         self.assertRaises(TypeError, solution.find_diff, None)
         self.assertEqual(solution.find_diff('ab', 'aab'), 'a')
         self.assertEqual(solution.find_diff('aab', 'ab'), 'a')
+        self.assertEqual(solution.find_diff('baa', 'ab'), 'a')
         self.assertEqual(solution.find_diff('abcd', 'abcde'), 'e')
         self.assertEqual(solution.find_diff('aaabbcdd', 'abdbacade'), 'e')
         self.assertEqual(solution.find_diff_xor('ab', 'aab'), 'a')