diff --git a/polymer-ui-icon/polymer-ui-icon.html b/polymer-ui-icon/polymer-ui-icon.html
index 0ca34fa..a8e2266 100644
--- a/polymer-ui-icon/polymer-ui-icon.html
+++ b/polymer-ui-icon/polymer-ui-icon.html
@@ -155,8 +155,10 @@
       var themes = {};
       function calcThemeOffset(theme, node) {
         if (themes[theme] === undefined) {
-          var offset = parseFloat(
-              getComputedStyle(node).backgroundPosition.split(' ').shift());
+          var bp = getComputedStyle(node).backgroundPosition.split(' ');
+          // support 4 value syntax (https://code.google.com/p/chromium/issues/detail?id=310977)
+          var l = bp.length === 4 ? bp[1] : bp[0];
+          var offset = parseFloat(l);
           themes[theme] = offset;
         }
         return themes[theme];