diff --git a/src/components/state-history-charts.html b/src/components/state-history-charts.html
index 37550407f3..e32fa537c0 100644
--- a/src/components/state-history-charts.html
+++ b/src/components/state-history-charts.html
@@ -8,6 +8,7 @@
 
 <dom-module id="state-history-charts">
   <template>
+    <link href="https://ajax.googleapis.com/ajax/static/modules/gviz/1.0/core/tooltip.css" rel="stylesheet" type="text/css">
     <style>
     :host {
       display: block;