diff --git a/BizHawk.Emulation.Common/Interfaces/IDebuggable.cs b/BizHawk.Emulation.Common/Interfaces/IDebuggable.cs
index 2f680eaa62..15504e236e 100644
--- a/BizHawk.Emulation.Common/Interfaces/IDebuggable.cs
+++ b/BizHawk.Emulation.Common/Interfaces/IDebuggable.cs
@@ -33,70 +33,118 @@ namespace BizHawk.Emulation.Common
 
 	public class RegisterValue
 	{
-		public ulong Value { get; set; }
-		public byte BitSize { get; set; }
+		public ulong Value { get; private set; }
+		public byte BitSize { get; private set; }
+
+		public RegisterValue(ulong val, byte bitSize)
+		{
+			if (bitSize == 64)
+				Value = val;
+			else if (bitSize > 64 || bitSize == 0)
+				throw new System.ArgumentOutOfRangeException("bitSize", "BitSize must be in 1..64");
+			else
+				Value = val & (1UL << bitSize) - 1;
+			BitSize = bitSize;
+		}
+
+		public RegisterValue(bool val)
+		{
+			Value = val ? 1UL : 0UL;
+			BitSize = 1;
+		}
+
+		public RegisterValue(byte val)
+		{
+			Value = val;
+			BitSize = 8;
+		}
+
+		public RegisterValue(sbyte val)
+		{
+			Value = (byte)val;
+			BitSize = 8;
+		}
+
+		public RegisterValue(ushort val)
+		{
+			Value = val;
+			BitSize = 16;
+		}
+
+		public RegisterValue(short val)
+		{
+			Value = (ushort)val;
+			BitSize = 16;
+		}
+
+		public RegisterValue(uint val)
+		{
+			Value = val;
+			BitSize = 32;
+		}
+
+		public RegisterValue(int val)
+		{
+			Value = (uint)val;
+			BitSize = 32;
+		}
+
+		public RegisterValue(ulong val)
+		{
+			Value = val;
+			BitSize = 64;
+		}
+
+		public RegisterValue(long val)
+		{
+			Value = (ulong)val;
+			BitSize = 64;
+		}
+
 
 		public static implicit operator RegisterValue(bool val)
 		{
-			return new RegisterValue
-			{
-				Value = (ulong)(val ? 1 : 0),
-				BitSize = 1
-			};
+			return new RegisterValue(val);
 		}
 
 		public static implicit operator RegisterValue(byte val)
 		{
-			return new RegisterValue
-			{
-				Value = val,
-				BitSize = 8
-			};
+			return new RegisterValue(val);
+		}
+
+		public static implicit operator RegisterValue(sbyte val)
+		{
+			return new RegisterValue(val);
 		}
 
 		public static implicit operator RegisterValue(ushort val)
 		{
-			return new RegisterValue
-			{
-				Value = val,
-				BitSize = 16
-			};
+			return new RegisterValue(val);
 		}
 
-		public static implicit operator RegisterValue(int val)
+		public static implicit operator RegisterValue(short val)
 		{
-			return new RegisterValue
-			{
-				Value = (ulong)val,
-				BitSize = 32
-			};
+			return new RegisterValue(val);
 		}
 
 		public static implicit operator RegisterValue(uint val)
 		{
-			return new RegisterValue
-			{
-				Value = val,
-				BitSize = 32
-			};
+			return new RegisterValue(val);
 		}
 
-		public static implicit operator RegisterValue(long val)
+		public static implicit operator RegisterValue(int val)
 		{
-			return new RegisterValue
-			{
-				Value = (ulong)val,
-				BitSize = 64
-			};
+			return new RegisterValue(val);
 		}
 
 		public static implicit operator RegisterValue(ulong val)
 		{
-			return new RegisterValue
-			{
-				Value = val,
-				BitSize = 64
-			};
+			return new RegisterValue(val);
+		}
+
+		public static implicit operator RegisterValue(long val)
+		{
+			return new RegisterValue(val);
 		}
 	}
 }
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDebuggable.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDebuggable.cs
index 9f8ddf7341..671d2ff774 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDebuggable.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.IDebuggable.cs
@@ -24,15 +24,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 				if (name.Contains("68K SR") || name.StartsWith("Z80"))
 					size = 16;
 
-				// TODO: clean me up
-				if (size == 16)
-				{
-					ret[Marshal.PtrToStringAnsi(regs[i].Name)] = (ushort)regs[i].Value;
-				}
-				else
-				{
-					ret[Marshal.PtrToStringAnsi(regs[i].Name)] = (uint)regs[i].Value;
-				}
+				ret[name] = new RegisterValue((ulong)regs[i].Value, size);
 			}
 
 			return ret;