diff --git a/code-ch11/Chapter11.ipynb b/code-ch11/Chapter11.ipynb
index 1eaca6f7..cefb11f3 100644
--- a/code-ch11/Chapter11.ipynb
+++ b/code-ch11/Chapter11.ipynb
@@ -16,7 +16,8 @@
     "import helper\n",
     "import network\n",
     "import script\n",
-    "import tx"
+    "import tx\n",
+    "import merkleblock"
    ]
   },
   {