diff --git a/engine/tutorials/dockerimages.md b/engine/tutorials/dockerimages.md
index 45b00a085e..06713dfe47 100644
--- a/engine/tutorials/dockerimages.md
+++ b/engine/tutorials/dockerimages.md
@@ -189,7 +189,7 @@ you'd like to update.
 
 Inside our running container first let's update Ruby:
 
-    root@0b2616b0e5a8:/# apt-get install -y ruby2.0-dev
+    root@0b2616b0e5a8:/# apt-get install -y ruby2.0-dev ruby2.0
 
 Now let's add the `json` gem.