diff --git a/Terminal.Gui/Core/MainLoop.cs b/Terminal.Gui/Core/MainLoop.cs
index 4988a5a8e..43789e228 100644
--- a/Terminal.Gui/Core/MainLoop.cs
+++ b/Terminal.Gui/Core/MainLoop.cs
@@ -6,6 +6,7 @@
 //
 using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 
 namespace Terminal.Gui {
 	/// <summary>
@@ -61,6 +62,11 @@ namespace Terminal.Gui {
 
 		internal SortedList<long, Timeout> timeouts = new SortedList<long, Timeout> ();
 		object timeoutsLockToken = new object ();
+
+		/// <summary>
+		/// The idle handlers and lock that must be held while manipulating them
+		/// </summary>
+		object idleHandlersLock = new object ();
 		internal List<Func<bool>> idleHandlers = new List<Func<bool>> ();
 
 		/// <summary>
@@ -71,9 +77,15 @@ namespace Terminal.Gui {
 		public SortedList<long, Timeout> Timeouts => timeouts;
 
 		/// <summary>
-		/// Gets the list of all idle handlers.
+		/// Gets a copy of the list of all idle handlers.
 		/// </summary>
-		public List<Func<bool>> IdleHandlers => idleHandlers;
+		public ReadOnlyCollection<Func<bool>> IdleHandlers {
+			get {
+				lock (idleHandlersLock) {
+					return new List<Func<bool>> (idleHandlers).AsReadOnly ();
+				}
+			}
+		}
 
 		/// <summary>
 		/// The current IMainLoopDriver in use.
@@ -123,7 +135,7 @@ namespace Terminal.Gui {
 		/// <param name="idleHandler">Token that can be used to remove the idle handler with <see cref="RemoveIdle(Func{bool})"/> .</param>
 		public Func<bool> AddIdle (Func<bool> idleHandler)
 		{
-			lock (idleHandlers) {
+			lock (idleHandlersLock) {
 				idleHandlers.Add (idleHandler);
 			}
 
@@ -139,7 +151,7 @@ namespace Terminal.Gui {
 		///  This method also returns <c>false</c> if the idle handler is not found.
 		public bool RemoveIdle (Func<bool> token)
 		{
-			lock (token)
+			lock (idleHandlersLock)
 				return idleHandlers.Remove (token);
 		}
 
@@ -242,14 +254,14 @@ namespace Terminal.Gui {
 		void RunIdle ()
 		{
 			List<Func<bool>> iterate;
-			lock (idleHandlers) {
+			lock (idleHandlersLock) {
 				iterate = idleHandlers;
 				idleHandlers = new List<Func<bool>> ();
 			}
 
 			foreach (var idle in iterate) {
 				if (idle ())
-					lock (idleHandlers)
+					lock (idleHandlersLock)
 						idleHandlers.Add (idle);
 			}
 		}
@@ -294,7 +306,7 @@ namespace Terminal.Gui {
 
 			Driver.MainIteration ();
 
-			lock (idleHandlers) {
+			lock (idleHandlersLock) {
 				if (idleHandlers.Count > 0)
 					RunIdle ();
 			}
diff --git a/UnitTests/MainLoopTests.cs b/UnitTests/MainLoopTests.cs
index 69cff3e4b..1299c2b55 100644
--- a/UnitTests/MainLoopTests.cs
+++ b/UnitTests/MainLoopTests.cs
@@ -525,5 +525,63 @@ namespace Terminal.Gui.Core {
 		// - wait = false
 
 		// TODO: Add IMainLoop tests
+
+		volatile static int tbCounter = 0;
+
+		private static void Launch (Random r, TextField tf)
+		{
+			Task.Run (() => {
+				Thread.Sleep (r.Next (2, 4));
+				Application.MainLoop.Invoke (() => {
+					tf.Text = $"index{r.Next ()}";
+					Interlocked.Increment (ref tbCounter);
+				});
+			});
+		}
+
+		private static void RunTest (Random r, TextField tf, int numPasses, int numIncrements, int pollMs)
+		{
+			for (int j = 0; j < numPasses; j++) {
+				for (var i = 0; i < numIncrements; i++) {
+					Launch (r, tf);
+				}
+
+				while (tbCounter != (j + 1) * numIncrements) // Wait for tbCounter to reach expected value
+				{
+					var tbNow = tbCounter;
+					Thread.Sleep (pollMs);
+					if (tbCounter == tbNow) {
+						// No change after sleep: Idle handlers added via Application.MainLoop.Invoke have gone missing
+						Application.MainLoop.Invoke (() => Application.RequestStop ());
+						throw new TimeoutException (
+							$"Timeout: Increment lost. tbCounter ({tbCounter}) didn't " +
+							$"change after waiting {pollMs} ms. Failed to reach {(j + 1) * numIncrements} on pass {j + 1}");
+					}
+				};
+			}
+			Application.MainLoop.Invoke (() => Application.RequestStop ());
+		}
+
+		[Fact]
+		[AutoInitShutdown]
+		public async Task InvokeLeakTest ()
+		{
+			Random r = new ();
+			TextField tf = new ();
+			Application.Top.Add (tf);
+
+			const int numPasses = 10;
+			const int numIncrements = 10000;
+			const int pollMs = 500;
+
+			var task = Task.Run (() => RunTest (r, tf, numPasses, numIncrements, pollMs));
+
+			// blocks here until the RequestStop is processed at the end of the test
+			Application.Run ();
+
+			await task; // Propagate exception if any occurred
+
+			Assert.Equal ((numIncrements * numPasses), tbCounter);
+		}
 	}
 }