--- a/devtools/client/responsive.html/test/browser/browser_tab_remoteness_change.js
+++ b/devtools/client/responsive.html/test/browser/browser_tab_remoteness_change.js
@@ -36,9 +36,10 @@ add_task(function* () {
   yield load(tab.linkedBrowser, "about:robots");
 
   // This flag is set at the end of `ResponsiveUI.destroy`.  If it is true without
   // yielding on `closeRDM` itself and only removing the tab, then we must have closed
   // synchronously in response to tab closing.
   is(ui.destroyed, true, "RDM closed synchronously");
 
   yield clientClosed;
+  yield removeTab(tab);
 });

--- a/devtools/client/responsive.html/test/browser/head.js
+++ b/devtools/client/responsive.html/test/browser/head.js
@@ -360,18 +360,21 @@ function addDeviceForTest(device) {
   registerCleanupFunction(() => {
     // Note that assertions in cleanup functions are not displayed unless they failed.
     ok(removeDevice(device), `Removed Test Device "${device.name}" from the list.`);
   });
 }
 
 function waitForClientClose(ui) {
   return new Promise(resolve => {
-    info("RDM's debugger client is now closed");
-    ui.client.addOneTimeListener("closed", resolve);
+    info("Waiting for RDM debugger client to close");
+    ui.client.addOneTimeListener("closed", () => {
+      info("RDM's debugger client is now closed");
+      resolve();
+    });
   });
 }
 
 function* testTouchEventsOverride(ui, expected) {
   let { document } = ui.toolWindow;
   let touchButton = document.querySelector("#global-touch-simulation-button");
 
   let flag = yield ui.emulationFront.getTouchEventsOverride();