diff --git a/index.ipynb b/index.ipynb
index 2ae5742bb..f9da121f2 100644
--- a/index.ipynb
+++ b/index.ipynb
@@ -18,7 +18,7 @@
     "\n",
     "3. [**Search**](./search.ipynb)\n",
     "\n",
-    "4. [**Search - 4th edition**](./search-4e.ipynb)\n",
+    "4. [**Search - 4th edition**](./search4e.ipynb)\n",
     "\n",
     "4. [**Games**](./games.ipynb)\n",
     "\n",