diff --git a/BizHawk.Emulation.Common/Base Implementations/MemoryDomainList.cs b/BizHawk.Emulation.Common/Base Implementations/MemoryDomainList.cs
index b9dd915503..973adb76b7 100644
--- a/BizHawk.Emulation.Common/Base Implementations/MemoryDomainList.cs	
+++ b/BizHawk.Emulation.Common/Base Implementations/MemoryDomainList.cs	
@@ -84,5 +84,36 @@ namespace BizHawk.Emulation.Common
 				_systemBus = value;
 			}
 		}
+
+		/// <summary>
+		/// for core use only
+		/// </summary>
+		public void MergeList(MemoryDomainList other)
+		{
+			var domains = this.ToDictionary(m => m.Name);
+			foreach (var src in other)
+			{
+				MemoryDomain dst;
+				if (domains.TryGetValue(src.Name, out dst))
+				{
+					TryMerge<MemoryDomainByteArray>(dst, src, (d, s) => d.Data = s.Data);
+					TryMerge<MemoryDomainIntPtr>(dst, src, (d, s) => d.Data = s.Data);
+					TryMerge<MemoryDomainIntPtrSwap16>(dst, src, (d, s) => d.Data = s.Data);
+					TryMerge<MemoryDomainDelegate>(dst, src, (d, s) => { d.Peek = s.Peek; d.Poke = s.Poke; });
+				}
+			}
+		}
+
+		/// <summary>
+		/// big hacks
+		/// </summary>
+		private static void TryMerge<T>(MemoryDomain dest, MemoryDomain src, Action<T, T> func)
+			where T : MemoryDomain
+		{
+			var d1 = dest as T;
+			var s1 = src as T;
+			if (d1 != null && s1 != null)
+				func(d1, s1);
+		}
 	}
 }
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IMemoryDomains.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IMemoryDomains.cs
index ca834d73b4..0997f6e269 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IMemoryDomains.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IMemoryDomains.cs
@@ -9,6 +9,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 	public partial class NES
 	{
 		private MemoryDomainList _memoryDomains;
+		private bool _memoryDomainsSetup = false;
 
 		private void SetupMemoryDomains()
 		{
@@ -67,8 +68,17 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 				domains.Add((Board as ExROM).GetExRAM());
 			}
 
-			_memoryDomains = new MemoryDomainList(domains);
-			(ServiceProvider as BasicServiceProvider).Register<IMemoryDomains>(_memoryDomains);
+			if (!_memoryDomainsSetup)
+			{
+				_memoryDomains = new MemoryDomainList(domains);
+				(ServiceProvider as BasicServiceProvider).Register<IMemoryDomains>(_memoryDomains);
+				_memoryDomainsSetup = true;
+			}
+			else
+			{
+				var src = new MemoryDomainList(domains);
+				_memoryDomains.MergeList(src);
+			}
 		}
 	}
 }
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IStatable.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IStatable.cs
index 2ac1a434a5..29bc7d39e3 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IStatable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.IStatable.cs
@@ -23,6 +23,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 		public void LoadStateText(TextReader reader)
 		{
 			SyncState(Serializer.CreateTextReader(reader));
+			SetupMemoryDomains(); // resync the memory domains
 		}
 
 		public void SaveStateBinary(BinaryWriter bw)
@@ -33,6 +34,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 		public void LoadStateBinary(BinaryReader br)
 		{
 			SyncState(Serializer.CreateBinaryReader(br));
+			SetupMemoryDomains(); // resync the memory domains
 		}
 
 		public byte[] SaveStateBinary()