diff --git a/plugins/icon.rb b/plugins/icon.rb
index 95d45b58bdc..268bd6a7354 100644
--- a/plugins/icon.rb
+++ b/plugins/icon.rb
@@ -13,7 +13,7 @@ module Jekyll
             #{args}
 
             Valid syntax:
-              {% icon "<icon>" %}
+              {% icon "<icon-set>:<icon-name>" %}
           MSG
         end
       end
@@ -24,7 +24,7 @@ module Jekyll
 
       private
 
-      SYNTAX = %r!^"(.+?)"$!.freeze
+      SYNTAX = %r!^"([a-z0-9]+(?:-[a-z0-9]+)*:[a-z0-9]+(?:-[a-z0-9]+)*)"$!.freeze
     end
   end
 end
diff --git a/source/dashboards/cards.markdown b/source/dashboards/cards.markdown
index d457e80322b..4fbf8ed25dd 100644
--- a/source/dashboards/cards.markdown
+++ b/source/dashboards/cards.markdown
@@ -112,7 +112,7 @@ In [sections view](/dashboards/sections/), you can resize cards. Follow these st
 
 If you previously [resized](#resizing-a-card) a card in the [sections view](/dashboards/sections/), and you don't like the new size, you can revert back to the card's default size. Follow these steps:
 
-1. On the **Layout** tab, select the {% icon "mdi-restore" %} icon.
+1. On the **Layout** tab, select the {% icon "mdi:restore" %} icon.
    ![Screenshot of the Layout tab in the card dialog](/images/dashboards/card_resize.png)
 
 2. Select **Save**.