diff --git a/nixos/tests/mumble.nix b/nixos/tests/mumble.nix
index 35f440026997..7959b85a0cf0 100644
--- a/nixos/tests/mumble.nix
+++ b/nixos/tests/mumble.nix
@@ -36,18 +36,29 @@ in
     # cancel client audio configuration
     $client1->waitForWindow(qr/Audio Tuning Wizard/);
     $client2->waitForWindow(qr/Audio Tuning Wizard/);
+    $server->sleep(5); # wait because mumble is slow to register event handlers
     $client1->sendKeys("esc");
     $client2->sendKeys("esc");
 
     # cancel client cert configuration
     $client1->waitForWindow(qr/Certificate Management/);
     $client2->waitForWindow(qr/Certificate Management/);
+    $server->sleep(5); # wait because mumble is slow to register event handlers
     $client1->sendKeys("esc");
     $client2->sendKeys("esc");
 
     # accept server certificate
     $client1->waitForWindow(qr/^Mumble$/);
     $client2->waitForWindow(qr/^Mumble$/);
+    $server->sleep(5); # wait because mumble is slow to register event handlers
+    $client1->sendChars("y");
+    $client2->sendChars("y");
+    $server->sleep(5); # wait because mumble is slow to register event handlers
+
+    # sometimes the wrong of the 2 windows is focused, we switch focus and try pressing "y" again
+    $client1->sendKeys("alt-tab");
+    $client2->sendKeys("alt-tab");
+    $server->sleep(5); # wait because mumble is slow to register event handlers
     $client1->sendChars("y");
     $client2->sendChars("y");