diff --git a/docs/installation/ubuntulinux.md b/docs/installation/ubuntulinux.md
index 0e632bde2b..6bcf222fa0 100644
--- a/docs/installation/ubuntulinux.md
+++ b/docs/installation/ubuntulinux.md
@@ -127,7 +127,11 @@ install Docker using the following:
     >
     >       $ wget -qO- https://get.docker.com/gpg | sudo apt-key add -
 
-4. Verify `docker` is installed correctly.
+4. Start `docker`.
+
+        $ sudo service docker start
+
+5. Verify `docker` is installed correctly.
 
         $ sudo docker run hello-world