diff --git a/examples/Isosurface.ipynb b/examples/Isosurface.ipynb
index 93a1f34..70af71f 100644
--- a/examples/Isosurface.ipynb
+++ b/examples/Isosurface.ipynb
@@ -33,7 +33,7 @@
     "!{sys.executable} -m pip install SimpleITK\n",
     "!{sys.executable} -m pip install simpleitkutilities\n",
     "!{sys.executable} -m pip install vtk\n",
-    "!{sys.executable} -m pip install itkwidgets"
+    "!{sys.executable} -m pip install itkwidgets",
     "!{sys.executable} -m pip install pydicom"
    ]
   },