diff --git a/BizHawk.Emulation.Common/EmulationExceptions.cs b/BizHawk.Emulation.Common/EmulationExceptions.cs
index 75c4360c5e..6847a077d8 100644
--- a/BizHawk.Emulation.Common/EmulationExceptions.cs
+++ b/BizHawk.Emulation.Common/EmulationExceptions.cs
@@ -31,4 +31,13 @@ namespace BizHawk.Emulation.Common
 		{
 		}
 	}
+
+	public class SavestateSizeMismatchException : InvalidOperationException
+	{
+		public SavestateSizeMismatchException(string message)
+			: base(message)
+		{
+
+		}
+	}
 }
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/N64/N64.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/N64/N64.cs
index 7b8844a060..83917a7644 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/N64/N64.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/N64/N64.cs
@@ -327,8 +327,8 @@ namespace BizHawk.Emulation.Cores.Nintendo.N64
 			byte[] data = SaveStatePrivateBuff;
 			int bytes_used = api.SaveState(data);
 
-			writer.Write(data.Length);
-			writer.Write(data);
+			writer.Write(bytes_used);
+			writer.Write(data, 0, bytes_used);
 
 			byte[] saveram = api.SaveSaveram();
 			writer.Write(saveram);
@@ -346,6 +346,11 @@ namespace BizHawk.Emulation.Cores.Nintendo.N64
 		public void LoadStateBinary(BinaryReader reader)
 		{
 			int length = reader.ReadInt32();
+			if ((_syncSettings.DisableExpansionSlot && length >= 16788288) || (!_syncSettings.DisableExpansionSlot && length < 16788288))
+			{
+				throw new SavestateSizeMismatchException("Wrong N64 savestate size");
+			}
+
 			reader.Read(SaveStatePrivateBuff, 0, length);
 			byte[] data = SaveStatePrivateBuff;
 
diff --git a/libmupen64plus/mupen64plus-core/src/main/savestates.c b/libmupen64plus/mupen64plus-core/src/main/savestates.c
index eddd3d1e30..0fda5c49aa 100644
--- a/libmupen64plus/mupen64plus-core/src/main/savestates.c
+++ b/libmupen64plus/mupen64plus-core/src/main/savestates.c
@@ -483,7 +483,14 @@ EXPORT int CALL savestates_load_bkm(char * curr)
     size_t savestateSize;
     unsigned char *savestateData;
 
-    char *queue = curr + 16788288;
+	int hasExpansion;
+
+    char *queue;
+
+	hasExpansion = !(ConfigGetParamInt(g_CoreConfig, "DisableExtraMem"));
+	savestateSize = hasExpansion ? 16788288 : 12593984;
+	queue = curr + savestateSize;
+
 	curr += 44;
 
     // Parse savestate
@@ -595,7 +602,7 @@ EXPORT int CALL savestates_load_bkm(char * curr)
     dps_register.dps_buftest_addr = GETDATA(curr, unsigned int);
     dps_register.dps_buftest_data = GETDATA(curr, unsigned int);
 
-    COPYARRAY(rdram, curr, unsigned int, 0x800000/4);
+    COPYARRAY(rdram, curr, unsigned int, (hasExpansion ? 0x800000 : 0x400000) /4);
     COPYARRAY(SP_DMEM, curr, unsigned int, 0x1000/4);
     COPYARRAY(SP_IMEM, curr, unsigned int, 0x1000/4);
     COPYARRAY(PIF_RAM, curr, unsigned char, 0x40);
@@ -1446,10 +1453,21 @@ EXPORT int CALL savestates_save_bkm(char *curr)
     int queuelength;
 	int savestate_size;
 
+	int hasExpansion;
+
     queuelength = save_eventqueue_infos(queue);
 
+	hasExpansion = !(ConfigGetParamInt(g_CoreConfig, "DisableExtraMem"));
+
     // Allocate memory for the save state data
-    savestate_size = 16788288 + queuelength;
+	if (hasExpansion)
+	{
+		savestate_size = 16788288 + queuelength;
+	}
+	else
+	{
+		savestate_size = 12593984 + queuelength;
+	}
 
     // Write the save state data to memory
     PUTARRAY(savestate_magic, curr, unsigned char, 8);
@@ -1602,7 +1620,7 @@ EXPORT int CALL savestates_save_bkm(char *curr)
     PUTDATA(curr, unsigned int, dps_register.dps_buftest_addr);
     PUTDATA(curr, unsigned int, dps_register.dps_buftest_data);
 
-    PUTARRAY(rdram, curr, unsigned int, 0x800000/4);
+    PUTARRAY(rdram, curr, unsigned int, (hasExpansion ? 0x800000 : 0x400000) / 4);
     PUTARRAY(SP_DMEM, curr, unsigned int, 0x1000/4);
     PUTARRAY(SP_IMEM, curr, unsigned int, 0x1000/4);
     PUTARRAY(PIF_RAM, curr, unsigned char, 0x40);
@@ -1967,4 +1985,4 @@ void savestates_deinit(void)
 {
     SDL_DestroyMutex(savestates_lock);
     savestates_clear_job();
-}
+}
\ No newline at end of file
diff --git a/output/dll/mupen64plus.dll b/output/dll/mupen64plus.dll
index 8e3f324df7..4c7aca6221 100644
Binary files a/output/dll/mupen64plus.dll and b/output/dll/mupen64plus.dll differ