diff --git a/zephyr/static/js/narrow.js b/zephyr/static/js/narrow.js
index 2055f09d7f..2308917da5 100644
--- a/zephyr/static/js/narrow.js
+++ b/zephyr/static/js/narrow.js
@@ -164,7 +164,7 @@ exports.predicate = function () {
 
 exports.operators = function () {
     if (current_filter === undefined) {
-        return false;
+        return [];
     }
     return current_filter.operators();
 };
@@ -618,7 +618,7 @@ exports.by_stream_subject_uri = function (stream, subject) {
 exports.narrowed_to_pms = function () {
     // Are we narrowed to PMs: all PMs or PMs with particular people.
     var operators = narrow.operators();
-    if (!operators) {
+    if (operators.length === 0) {
         return false;
     }
     if ((operators[0][0] === "pm-with") ||
diff --git a/zephyr/static/js/subs.js b/zephyr/static/js/subs.js
index ee5e8b66ea..be2d69cb81 100644
--- a/zephyr/static/js/subs.js
+++ b/zephyr/static/js/subs.js
@@ -926,7 +926,7 @@ $(function () {
 
 function focus_on_narrowed_stream() {
     var operators = narrow.operators();
-    if (!operators) {
+    if (operators.length === 0) {
         return;
     }
     var stream_name = operators[0][1];