--- a/dom/tests/mochitest/pointerlock/file_targetOutOfFocus.html
+++ b/dom/tests/mochitest/pointerlock/file_targetOutOfFocus.html
@@ -38,17 +38,17 @@
 
         function runTests () {
           ok(divPointerLock, "Pointer should be locked even if " +
             "the element being locked is not focused");
         }
 
         input.addEventListener("focus", function() {
           div.requestPointerLock();
-        });
+        }, { once: true });
 
         document.addEventListener("pointerlockchange", function (e) {
           if (document.pointerLockElement === div) {
             divPointerLock = true;
             addFullscreenChangeContinuation("exit", function() {
               runTests();
               SimpleTest.finish();
             });