diff --git a/js/misc/util.js b/js/misc/util.js
index 36640580b..8673f8329 100644
--- a/js/misc/util.js
+++ b/js/misc/util.js
@@ -265,7 +265,7 @@ function lowerBound(array, val, cmp) {
             max = mid;
     }
 
-    return (cmp(array[min], val) < 0) ? max : min;
+    return (min == max || cmp(array[min], val) < 0) ? max : min;
 }
 
 // insertSorted:
diff --git a/tests/unit/insertSorted.js b/tests/unit/insertSorted.js
index e23848a22..610aeed56 100644
--- a/tests/unit/insertSorted.js
+++ b/tests/unit/insertSorted.js
@@ -64,8 +64,13 @@ let arrayEmpty = [];
 // inserting in a empty array
 Util.insertSorted(arrayEmpty, 3, checkedCmp);
 
+// Insert at the end and check that we don't
+// access past it
+Util.insertSorted(arrayEmpty, 4, checkedCmp);
+Util.insertSorted(arrayEmpty, 5, checkedCmp);
+
 // Some more insertions
 Util.insertSorted(arrayEmpty, 2, checkedCmp);
 Util.insertSorted(arrayEmpty, 1, checkedCmp);
 
-assertArrayEquals('checkedCmp test', [1, 2, 3], arrayEmpty);
+assertArrayEquals('checkedCmp test', [1, 2, 3, 4, 5], arrayEmpty);