diff --git a/tests/linker-ios/link all/LinkAllTest.cs b/tests/linker-ios/link all/LinkAllTest.cs
index b5fd67d0550e..83a6909752c2 100644
--- a/tests/linker-ios/link all/LinkAllTest.cs	
+++ b/tests/linker-ios/link all/LinkAllTest.cs	
@@ -15,6 +15,8 @@
 using System.Net;
 using System.Net.Security;
 using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
 using System.Security.Cryptography.X509Certificates;
 
 using MonoTouch;
@@ -542,5 +544,34 @@ public void WebKit_NSProxy ()
 			var fqn = typeof (NSObject).AssemblyQualifiedName.Replace ("Foundation.NSObject", "Foundation.NSProxy");
 			Assert.Null (Type.GetType (fqn), fqn);
 		}
+
+		[Test]
+		public void Bug59015 ()
+		{
+			CheckAsyncTaskMethodBuilder (typeof (AsyncTaskMethodBuilder));
+			CheckAsyncTaskMethodBuilder (typeof (AsyncTaskMethodBuilder<int>));
+			var t = typeof (Task);
+			var snfwc = t.GetMethod ("SetNotificationForWaitCompletion", BindingFlags.Instance | BindingFlags.NonPublic);
+#if DEBUG
+			Assert.NotNull (snfwc, "Task.NotifyDebuggerOfWaitCompletion");
+#else
+			// something keeps it from being removed
+			// Assert.Null (snfwc, "Task.NotifyDebuggerOfWaitCompletion");
+#endif
+		}
+
+		void CheckAsyncTaskMethodBuilder (Type atmb)
+		{
+			Assert.NotNull (atmb, "AsyncTaskMethodBuilder");
+			var snfwc = atmb.GetMethod ("SetNotificationForWaitCompletion", BindingFlags.Instance | BindingFlags.NonPublic);
+			var oifd = atmb.GetProperty ("ObjectIdForDebugger", BindingFlags.Instance | BindingFlags.NonPublic);
+#if DEBUG
+			Assert.NotNull (snfwc, atmb.FullName + ".SetNotificationForWaitCompletion");
+			Assert.NotNull (oifd,  atmb.FullName + ".ObjectIdForDebugger");
+#else
+			Assert.Null (snfwc, atmb.FullName + ".SetNotificationForWaitCompletion");
+			Assert.Null (oifd,  atmb.FullName + ".ObjectIdForDebugger");
+#endif
+		}
 	}
 }
diff --git a/tools/linker/MobileMarkStep.cs b/tools/linker/MobileMarkStep.cs
index 1f3a51e57713..5b2107ba715f 100644
--- a/tools/linker/MobileMarkStep.cs
+++ b/tools/linker/MobileMarkStep.cs
@@ -259,19 +259,25 @@ void MarkMetadata (IMetadataTokenProvider tp)
 		void ProcessCorlib (TypeDefinition type)
 		{
 			switch (type.Namespace) {
-			case "System.Runtime.CompilerServices.AsyncTaskMethodBuilder":
-				if (DebugBuild)
-					MarkNamedMethod (type, "SetNotificationForWaitCompletion");
-				break;
-			case "System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1":
-				if (DebugBuild)
-					MarkNamedMethod (type, "SetNotificationForWaitCompletion");
+			case "System.Runtime.CompilerServices":
+				switch (type.Name) {
+					case "AsyncTaskMethodBuilder":
+					case "AsyncTaskMethodBuilder`1":
+					if (DebugBuild) {
+						MarkNamedMethod (type, "SetNotificationForWaitCompletion");
+						MarkNamedMethod (type, "get_ObjectIdForDebugger");
+					}
+					break;
+				}
 				break;
-			case "System.Threading.Tasks.Task":
-				if (DebugBuild)
-					MarkNamedMethod (type, "NotifyDebuggerOfWaitCompletion");
+			case "System.Threading.Tasks":
+				switch (type.Name) {
+					case "Task":
+					if (DebugBuild)
+						MarkNamedMethod (type, "NotifyDebuggerOfWaitCompletion");
+					break;
+				}
 				break;
-
 			case "System.Security.Cryptography":
 				switch (type.Name) {
 				case "Aes":