diff --git a/lib/test-driver/Machine.pm b/lib/test-driver/Machine.pm
index 34ea4e5e65ce..a3c714b3a86a 100644
--- a/lib/test-driver/Machine.pm
+++ b/lib/test-driver/Machine.pm
@@ -287,4 +287,24 @@ sub screenshot {
 }
 
 
+sub getWindowNames {
+    my ($self) = @_;
+    my $res = $self->mustSucceed(
+        q{DISPLAY=:0.0 xwininfo -root -tree | sed 's/.*0x[0-9a-f]* \"\([^\"]*\)\".*/\1/; t; d'});
+    return split /\n/, $res;
+}
+
+
+sub waitForWindow {
+    my ($self, $regexp) = @_;
+    while (1) {
+        my @names = $self->getWindowNames;
+        foreach my $n (@names) {
+            return if $n =~ /$regexp/;
+        }
+        sleep 2;
+    }
+};
+
+
 1;
diff --git a/modules/testing/test-instrumentation.nix b/modules/testing/test-instrumentation.nix
index 2dd1a90b966e..a563852e22c0 100644
--- a/modules/testing/test-instrumentation.nix
+++ b/modules/testing/test-instrumentation.nix
@@ -48,6 +48,9 @@ with pkgs.lib;
     # Panic if an error occurs in stage 1 (rather than waiting for
     # user intervention). 
     boot.kernelParams = [ "stage1panic" ];
+
+    # `xwininfo' is used by the test driver to query open windows.
+    environment.systemPackages = [ pkgs.xorg.xwininfo ];
       
   };
 
diff --git a/tests/kde4.nix b/tests/kde4.nix
index f13b87b07633..3b91b738cb7f 100644
--- a/tests/kde4.nix
+++ b/tests/kde4.nix
@@ -36,18 +36,16 @@
 
   testScript =
     ''
-      $machine->waitForFile("/tmp/.X11-unix/X0");
-
-      sleep 70;
+      $machine->waitForWindow(qr/plasma-desktop/);
 
       $machine->execute("su - alice -c 'DISPLAY=:0.0 kwrite /var/log/messages &'");
-
-      sleep 10;
-      
       $machine->execute("su - alice -c 'DISPLAY=:0.0 konqueror http://localhost/ &'");
 
-      sleep 10;
+      $machine->waitForWindow(qr/messages.*KWrite/);
+      $machine->waitForWindow(qr/Valgrind.*Konqueror/);
 
+      sleep 5;
+      
       $machine->screenshot("screen");
     '';