diff --git a/5_nn/2-mlp_bp.ipynb b/5_nn/2-mlp_bp.ipynb
index 6336f13..c33abc1 100644
--- a/5_nn/2-mlp_bp.ipynb
+++ b/5_nn/2-mlp_bp.ipynb
@@ -4921,7 +4921,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.8"
+   "version": "3.5.2"
   }
  },
  "nbformat": 4,