diff --git a/controls.md b/controls.md
index 81c1e72a..bc536f0a 100644
--- a/controls.md
+++ b/controls.md
@@ -88,14 +88,14 @@ This is an example `html` option with all controls.
         "</span>",
     "</span>",
     "<span class='player-controls-right'>",
-        "<button type="button" data-player="mute">",
+        "<button type='button' data-player='mute'>",
             "<svg class='icon-muted'><use xlink:href='#icon-muted'></use></svg>",
             "<svg><use xlink:href='#icon-volume'></use></svg>",
             "<span class='sr-only'>Toggle Mute</span>",
         "</button>",
         "<label for='volume{id}' class='sr-only'>Volume</label>",
         "<input id='volume{id}' class='player-volume' type='range' min='0' max='10' value='5' data-player='volume'>",
-        "<button type="button" data-player="captions">",
+        "<button type='button' data-player='captions'>",
             "<svg class='icon-captions-on'><use xlink:href='#icon-captions-on'></use></svg>",
             "<svg><use xlink:href='#icon-captions-off'></use></svg>",
             "<span class='sr-only'>Toggle Captions</span>",