diff --git a/tests/monotouch-test/CoreFoundation/BundleTest.cs b/tests/monotouch-test/CoreFoundation/BundleTest.cs
index 7c0707bf66b1..fca3809597b4 100644
--- a/tests/monotouch-test/CoreFoundation/BundleTest.cs
+++ b/tests/monotouch-test/CoreFoundation/BundleTest.cs
@@ -76,7 +76,7 @@ public void TestGetMain ()
 		{
 			var main = CFBundle.GetMain ();
 #if __WATCHOS__
-			var expectedBundleId = "com.xamarin.monotouch-test-watch.watchkitapp.watchkitextension";
+			var expectedBundleId = "com.xamarin.monotouch-test_watch.watchkitapp.watchkitextension";
 #elif MONOMAC
 			var expectedBundleId = "com.xamarin.xammac_tests";
 #else
diff --git a/tests/xharness/WatchOSTarget.cs b/tests/xharness/WatchOSTarget.cs
index badc67d202c1..40c91a7f0d8d 100644
--- a/tests/xharness/WatchOSTarget.cs
+++ b/tests/xharness/WatchOSTarget.cs
@@ -154,7 +154,7 @@ void CreateWatchOSExtensionProject ()
 			XmlDocument info_plist = new XmlDocument ();
 			var target_info_plist = Path.Combine (TargetDirectory, $"Info{Suffix}-extension.plist");
 			info_plist.LoadWithoutNetworkAccess (Path.Combine (TargetDirectory, "Info.plist"));
-			BundleIdentifier = info_plist.GetCFBundleIdentifier () + "-watch";
+			BundleIdentifier = info_plist.GetCFBundleIdentifier () + "_watch";
 			if (BundleIdentifier.Length >= 58)
 				BundleIdentifier = BundleIdentifier.Substring (0, 57); // If the main app's bundle id is 58 characters (or sometimes more), then the watch extension crashes at launch. radar #29847128.
 			info_plist.SetCFBundleIdentifier (BundleIdentifier + ".watchkitapp.watchkitextension");