--- a/devtools/client/netmonitor/test/browser_net_pane-toggle.js
+++ b/devtools/client/netmonitor/test/browser_net_pane-toggle.js
@@ -41,16 +41,18 @@ add_task(function* () {
     "collapsed after the first request.");
   is(NetMonitorView.detailsPaneHidden, true,
     "The details pane should still be hidden after the first request.");
   is(RequestsMenu.selectedItem, null,
     "There should still be no selected item in the requests menu.");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, toggleButton);
 
+  yield monitor.panelWin.once(TAB_UPDATED);
+
   is(toggleButton.hasAttribute("disabled"), false,
     "The pane toggle button should still be enabled after being pressed.");
   is(toggleButton.classList.contains("pane-collapsed"), false,
     "The pane toggle button should now indicate that the details pane is " +
     "not collapsed anymore after being pressed.");
   is(NetMonitorView.detailsPaneHidden, false,
     "The details pane should not be hidden after toggle button was pressed.");
   isnot(RequestsMenu.selectedItem, null,