diff --git a/app-header/app-header.html b/app-header/app-header.html
index 58fbc830..38bd2fb0 100644
--- a/app-header/app-header.html
+++ b/app-header/app-header.html
@@ -452,7 +452,7 @@ <h1 main-title>App name</h1>
         }
         var nodes = Polymer.dom(this.$.slot).getDistributedNodes();
         // Get the element with the sticky attribute on it or the first element in the light DOM.
-        for (var i = 0, node; node = nodes[i]; i++) {
+        for (var i = 0, node; node = /** @type {!HTMLElement} */ (nodes[i]); i++) {
           if (node.nodeType === Node.ELEMENT_NODE) {
             if (node.hasAttribute('sticky')) {
               this._stickyElRef = node;
diff --git a/app-scroll-effects/effects/parallax-background.html b/app-scroll-effects/effects/parallax-background.html
index 52fa2c02..7c49fb77 100644
--- a/app-scroll-effects/effects/parallax-background.html
+++ b/app-scroll-effects/effects/parallax-background.html
@@ -30,7 +30,7 @@
         if (isNaN(scalar)) {
           scalar = 0.8;
         }
-        fx.deltaBg = this._dHeight * scalar;
+        fx.deltaBg = (this._dHeight || 0) * scalar;
       } else {
         if (isNaN(scalar)) {
           scalar = 1;