diff --git a/lib/mixins/property-effects.html b/lib/mixins/property-effects.html
index f02a24b6db..c10078ae17 100644
--- a/lib/mixins/property-effects.html
+++ b/lib/mixins/property-effects.html
@@ -89,16 +89,16 @@
    * @param {string} type Type of effect to run
    * @param {Object} props Bag of current property changes
    * @param {Object=} oldProps Bag of previous values for changed properties
-   * @param {boolean} hasPaths True with `props` contains one or more paths
-   * @param {*} var_args Additional metadata to pass to effect function
+   * @param {boolean=} hasPaths True with `props` contains one or more paths
+   * @param {*=} extraArgs Additional metadata to pass to effect function
    * @private
    */
-  function runEffects(inst, effects, props, oldProps, hasPaths, ...args) {
+  function runEffects(inst, effects, props, oldProps, hasPaths, extraArgs) {
     if (effects) {
       let ran;
       let id = dedupeId++;
       for (let prop in props) {
-        if (runEffectsForProperty(inst, effects, id, prop, props, oldProps, hasPaths, ...args)) {
+        if (runEffectsForProperty(inst, effects, id, prop, props, oldProps, hasPaths, extraArgs)) {
           ran = true;
         }
       }
@@ -115,11 +115,11 @@
    * @param {string} prop Name of changed property
    * @param {*} props Changed properties
    * @param {*} oldProps Old properties
-   * @param {boolean} hasPaths True with `props` contains one or more paths
-   * @param {*} var_args Additional metadata to pass to effect function
+   * @param {boolean=} hasPaths True with `props` contains one or more paths
+   * @param {*=} extraArgs Additional metadata to pass to effect function
    * @private
    */
-  function runEffectsForProperty(inst, effects, dedupeId, prop, props, oldProps, hasPaths, ...args) {
+  function runEffectsForProperty(inst, effects, dedupeId, prop, props, oldProps, hasPaths, extraArgs) {
     let ran;
     let rootProperty = hasPaths ? Polymer.Path.root(prop) : prop;
     let fxs = effects[rootProperty];
@@ -130,7 +130,7 @@
           if (fx.info) {
             fx.info.lastRun = dedupeId;
           }
-          fx.fn(inst, prop, props, oldProps, fx.info, hasPaths, ...args);
+          fx.fn(inst, prop, props, oldProps, fx.info, hasPaths, extraArgs);
           ran = true;
         }
       }