diff --git a/ml4/2_5_1_Exercise.ipynb b/ml4/2_5_1_Exercise.ipynb
index 5c4c4b5..736515e 100644
--- a/ml4/2_5_1_Exercise.ipynb
+++ b/ml4/2_5_1_Exercise.ipynb
@@ -236,7 +236,7 @@
     "* [gplearn](http://gplearn.readthedocs.io/en/latest/index.html)\n",
     "* [scikit-allel](https://scikit-allel.readthedocs.io/en/latest/)\n",
     "* [sklearn-genetic](https://github.com/manuel-calzolari/sklearn-genetic)\n",
-    "* [sklearn-genetic-opt](https://sklearn-genetic-opt.readthedocs.io/en/stable/)
+    "* [sklearn-genetic-opt](https://sklearn-genetic-opt.readthedocs.io/en/stable/)"
    ]
   },
   {