diff --git a/examples/How_to_count_tokens_with_tiktoken.ipynb b/examples/How_to_count_tokens_with_tiktoken.ipynb
index 42eecc9..362b267 100644
--- a/examples/How_to_count_tokens_with_tiktoken.ipynb
+++ b/examples/How_to_count_tokens_with_tiktoken.ipynb
@@ -465,7 +465,7 @@
     "        return num_tokens_from_messages(messages, model=\"gpt-4-0613\")\n",
     "    else:\n",
     "        raise NotImplementedError(\n",
-    "            f\"\"\"num_tokens_from_messages() is not implemented for model {model}. See https://github.com/openai/openai-python/blob/main/chatml.md for information on how messages are converted to tokens.\"\"\"\n",
+    "            f\"\"\"num_tokens_from_messages() is not implemented for model {model}.\"\"\"\n",
     "        )\n",
     "    num_tokens = 0\n",
     "    for message in messages:\n",
diff --git a/examples/How_to_format_inputs_to_ChatGPT_models.ipynb b/examples/How_to_format_inputs_to_ChatGPT_models.ipynb
index 847d45b..d08fb9c 100644
--- a/examples/How_to_format_inputs_to_ChatGPT_models.ipynb
+++ b/examples/How_to_format_inputs_to_ChatGPT_models.ipynb
@@ -543,7 +543,7 @@
     "        return num_tokens_from_messages(messages, model=\"gpt-4-0613\")\n",
     "    else:\n",
     "        raise NotImplementedError(\n",
-    "            f\"\"\"num_tokens_from_messages() is not implemented for model {model}. See https://github.com/openai/openai-python/blob/main/chatml.md for information on how messages are converted to tokens.\"\"\"\n",
+    "            f\"\"\"num_tokens_from_messages() is not implemented for model {model}.\"\"\"\n",
     "        )\n",
     "    num_tokens = 0\n",
     "    for message in messages:\n",