diff --git a/apps/p4-tutorial/exercise-1.md b/apps/p4-tutorial/exercise-1.md
index 3db67c0..2ebba43 100644
--- a/apps/p4-tutorial/exercise-1.md
+++ b/apps/p4-tutorial/exercise-1.md
@@ -366,6 +366,12 @@
 
 4. You can visualize the topology using the ONOS web UI.
 
+    Enter the following command to **activate the web interface**:
+
+        ```
+        onos> app activate org.onosproject.gui
+        ```
+
     Open a browser from within the tutorial VM (e.g. Firefox) to
     <http://127.0.0.1:8181/onos/ui/>. When asked, use the username `onos`
     and password `rocks`. You should see a nice tree topology.