diff --git a/code-ch09/Chapter9.ipynb b/code-ch09/Chapter9.ipynb
index 3546249d..917d5b3f 100644
--- a/code-ch09/Chapter9.ipynb
+++ b/code-ch09/Chapter9.ipynb
@@ -310,6 +310,7 @@
    "source": [
     "# Exercise 9\n",
     "\n",
+    "reload(helper)\n",
     "reload(block)\n",
     "run(block.BlockTest(\"test_target\"))"
    ]