diff --git a/dist/js/axs_testing.js b/dist/js/axs_testing.js
index eda2d713..1fe815bc 100644
--- a/dist/js/axs_testing.js
+++ b/dist/js/axs_testing.js
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
- * Generated from http://github.com/GoogleChrome/accessibility-developer-tools/tree/88731e16c8639738a1375f8c2de1ec2a23fcb631
+ * Generated from http://github.com/GoogleChrome/accessibility-developer-tools/tree/08b3be1e095d0203a094b370c27f77446a6c69e9
  *
  * See project README for build steps.
  */
@@ -1549,7 +1549,7 @@ axs.AuditRule.collectMatchingElements = function(a, b, c, d) {
         console.warn("ShadowRoot not provided for", e);
       }
     }
-    e && "iframe" == e.localName && axs.AuditRule.collectMatchingElements(a.contentDocument, b, c, d);
+    e && "iframe" == e.localName && e.contentDocument && axs.AuditRule.collectMatchingElements(e.contentDocument, b, c, d);
     for (a = a.firstChild;null != a;) {
       axs.AuditRule.collectMatchingElements(a, b, c, d), a = a.nextSibling;
     }
@@ -1866,7 +1866,8 @@ axs.AuditRules.addRule({name:"focusableElementNotVisibleAndNotAriaHidden", headi
       return !1;
     }
   }
-  return "" === axs.properties.findTextAlternatives(a, {}).trim() ? !1 : !0;
+  a = axs.properties.findTextAlternatives(a, {});
+  return null == a || "" === a.trim() ? !1 : !0;
 }, test:function(a) {
   if (axs.utils.isElementOrAncestorHidden(a)) {
     return !1;
diff --git a/src/audits/FocusableElementNotVisibleAndNotAriaHidden.js b/src/audits/FocusableElementNotVisibleAndNotAriaHidden.js
index f2726ac6..d4e07978 100644
--- a/src/audits/FocusableElementNotVisibleAndNotAriaHidden.js
+++ b/src/audits/FocusableElementNotVisibleAndNotAriaHidden.js
@@ -42,7 +42,8 @@ axs.AuditRules.addRule({
         }
         // Ignore elements which have a negative tabindex and no text content,
         // as they will be skipped by assistive technology
-        if (axs.properties.findTextAlternatives(element, {}).trim() === '')
+        var alternative = axs.properties.findTextAlternatives(element, {});
+        if (alternative == null || alternative.trim() === '')
             return false;
 
         return true;
diff --git a/src/js/AuditRule.js b/src/js/AuditRule.js
index 751d8b9f..275444cd 100644
--- a/src/js/AuditRule.js
+++ b/src/js/AuditRule.js
@@ -184,8 +184,8 @@ axs.AuditRule.collectMatchingElements = function(node, matcher, collection,
     }
 
     //If it is a iframe, get the contentDocument
-    if (element && element.localName == 'iframe') {
-        axs.AuditRule.collectMatchingElements(node.contentDocument,
+    if (element && element.localName == 'iframe' && element.contentDocument) {
+        axs.AuditRule.collectMatchingElements(element.contentDocument,
                                               matcher,
                                               collection,
                                               opt_shadowRoot);