diff --git a/graphs_trees/bst_validate/bst_validate_solution.ipynb b/graphs_trees/bst_validate/bst_validate_solution.ipynb
index 3b3dd7b..fbf1258 100644
--- a/graphs_trees/bst_validate/bst_validate_solution.ipynb
+++ b/graphs_trees/bst_validate/bst_validate_solution.ipynb
@@ -120,7 +120,7 @@
     "\n",
     "    def validate(self):\n",
     "        if self.root is None:\n",
-    "            raise Exception('No root node')\n",
+    "            raise TypeError('No root node')\n",
     "        return self._validate(self.root)\n",
     "\n",
     "    def _validate(self, node, mininum=-sys.maxsize, maximum=sys.maxsize):\n",