diff --git a/src/lib/style-properties.html b/src/lib/style-properties.html
index b485a09829..161b9d1c0b 100644
--- a/src/lib/style-properties.html
+++ b/src/lib/style-properties.html
@@ -285,6 +285,11 @@
         return {properties: props, key: o};
       },
 
+      _checkRoot: function(hostScope, selector) {
+        return selector.indexOf(':root') === 0 ||
+          (hostScope === 'html' && selector.indexOf('html') === 0);
+      },
+
       whenHostOrRootRule: function(scope, rule, style, callback) {
         if (!rule.propertyInfo) {
           self.decorateRule(rule);
@@ -292,14 +297,11 @@
         if (!rule.propertyInfo.properties) {
           return;
         }
-        var checkRoot = function(hostScope, selector) {
-          return selector.indexOf(':root') === 0 || (hostScope === 'html' && selector.indexOf('html') === 0);
-        };
         var hostScope = scope.is ?
         styleTransformer._calcHostScope(scope.is, scope.extends) :
         'html';
         var parsedSelector = rule.parsedSelector;
-        var isRoot = checkRoot(hostScope, parsedSelector);
+        var isRoot = this._checkRoot(hostScope, parsedSelector);
         var isHost = parsedSelector.indexOf(':host') === 0;
         // build info is either in scope (when scope is an element) or in the style
         // when scope is the default scope; note: this allows default scope to have
@@ -312,7 +314,7 @@
           isHost = !isRoot && parsedSelector.indexOf(hostScope) === 0;
         }
         if (cssBuild === 'shadow') {
-          isRoot = parsedSelector === ':host > *' || checkRoot(hostScope, parsedSelector);
+          isRoot = parsedSelector === ':host > *' || this._checkRoot(hostScope, parsedSelector);
           isHost = isHost && !isRoot;
         }
         if (!isRoot && !isHost) {