diff --git a/BizHawk.Emulation.Common/Base Implementations/MemoryCallbackSystem.cs b/BizHawk.Emulation.Common/Base Implementations/MemoryCallbackSystem.cs
index 052a191b58..ea2fa89649 100644
--- a/BizHawk.Emulation.Common/Base Implementations/MemoryCallbackSystem.cs	
+++ b/BizHawk.Emulation.Common/Base Implementations/MemoryCallbackSystem.cs	
@@ -14,13 +14,26 @@ namespace BizHawk.Emulation.Common
 
 		bool empty = true;
 
+		private bool _hasReads = false;
+		private bool _hasWrites = false;
+		private bool _hasExecutes = false;
+
 		public void Add(IMemoryCallback callback)
 		{
 			switch (callback.Type)
 			{
-				case MemoryCallbackType.Execute: Execs.Add(callback); break;
-				case MemoryCallbackType.Read: Reads.Add(callback); break;
-				case MemoryCallbackType.Write: Writes.Add(callback); break;
+				case MemoryCallbackType.Execute:
+					Execs.Add(callback);
+					_hasExecutes = true;
+					break;
+				case MemoryCallbackType.Read:
+					Reads.Add(callback);
+					_hasReads = true;
+					break;
+				case MemoryCallbackType.Write:
+					Writes.Add(callback);
+					_hasWrites = true;
+					break;
 			}
 			if (empty)
 				Changes();
@@ -53,17 +66,24 @@ namespace BizHawk.Emulation.Common
 
 		public bool HasReads
 		{
-			get { return Reads.Count > 0; }
+			get { return _hasReads; }
 		}
 
 		public bool HasWrites
 		{
-			get { return Writes.Count > 0; }
+			get { return _hasWrites; }
 		}
 
 		public bool HasExecutes
 		{
-			get { return Execs.Count > 0; }
+			get { return _hasExecutes; }
+		}
+
+		private void UpdateHasVariables()
+		{
+			_hasReads = Reads.Count > 0;
+			_hasWrites = Reads.Count > 0;
+			_hasExecutes = Reads.Count > 0;
 		}
 
 		private int RemoveInternal(Action action)
@@ -72,6 +92,9 @@ namespace BizHawk.Emulation.Common
 			ret += Reads.RemoveAll(imc => imc.Callback == action);
 			ret += Writes.RemoveAll(imc => imc.Callback == action);
 			ret += Execs.RemoveAll(imc => imc.Callback == action);
+
+			UpdateHasVariables();
+
 			return ret;
 		}
 
@@ -100,6 +123,8 @@ namespace BizHawk.Emulation.Common
 					Changes();
 				empty = newEmpty;
 			}
+
+			UpdateHasVariables();
 		}
 
 		public void Clear()
@@ -110,6 +135,8 @@ namespace BizHawk.Emulation.Common
 			if (!empty)
 				Changes();
 			empty = true;
+
+			UpdateHasVariables();
 		}
 
 		public delegate void ActiveChangedEventHandler();