diff --git a/Emux.GameBoy/Cpu/GameBoyCpu.cs b/Emux.GameBoy/Cpu/GameBoyCpu.cs
index 266b10d..412c504 100644
--- a/Emux.GameBoy/Cpu/GameBoyCpu.cs
+++ b/Emux.GameBoy/Cpu/GameBoyCpu.cs
@@ -27,6 +27,7 @@ namespace Emux.GameBoy.Cpu
 		private ulong _ticks;
         public bool IsBroken = true;
         public bool Halted = false;
+        private readonly Z80Instruction _readInstruction = new Z80Instruction(0, Z80OpCodes.SingleByteOpCodes[0], new byte[0]);
 
         public GameBoyCpu(GameBoy device, IClock clock)
         {
@@ -176,10 +177,8 @@ namespace Emux.GameBoy.Cpu
 
         private Z80Instruction ReadNextInstruction()
         {
-            _disassembler.Position = Registers.PC;
-            var instruction = _disassembler.ReadNextInstruction();
-            Registers.PC = _disassembler.Position;
-            return instruction;
+            _disassembler.ReadInstruction(ref Registers.PC, _readInstruction);
+            return _readInstruction;
         }
 
         internal void Push(ushort value)
diff --git a/Emux.GameBoy/Cpu/Z80Disassembler.cs b/Emux.GameBoy/Cpu/Z80Disassembler.cs
index aaf436e..0bcf78c 100644
--- a/Emux.GameBoy/Cpu/Z80Disassembler.cs
+++ b/Emux.GameBoy/Cpu/Z80Disassembler.cs
@@ -8,36 +8,29 @@ namespace Emux.GameBoy.Cpu
     public class Z80Disassembler 
     {
         private readonly GameBoyMemory _memory;
-        private readonly Z80Instruction _readInstruction = new Z80Instruction(0, Z80OpCodes.SingleByteOpCodes[0], new byte[0]);
 
         public Z80Disassembler(GameBoyMemory memory)
         {
             _memory = memory;
         }
 
-		/// <summary>
-		/// Gets or sets the position of the disassembler to read the next instruction from.
-		/// </summary>
-		public ushort Position { get; set; }
-
 		/// <summary>
 		/// Reads the next instruction from memory.
 		/// </summary>
 		/// <returns>The disassembled instruction.</returns>
-		public Z80Instruction ReadNextInstruction()
+		public void ReadInstruction(ref ushort location, Z80Instruction outInstruction)
         {
-            ushort offset = Position;
-            byte code = _memory.ReadByte(Position++);
+            ushort offset = location;
+            byte code = _memory.ReadByte(location++);
 
             var opcode = code != Z80OpCodes.ExtendedTableOpcode
                 ? Z80OpCodes.SingleByteOpCodes[code]
-                : Z80OpCodes.PrefixedOpCodes[_memory.ReadByte(Position++)];
+                : Z80OpCodes.PrefixedOpCodes[_memory.ReadByte(location++)];
 
-            var operands = _memory.ReadBytes(Position, opcode.OperandLength);
-            Position += (ushort)operands.Length;
+            var operands = _memory.ReadBytes(location, opcode.OperandLength);
+            location += (ushort)operands.Length;
 
-            _readInstruction.Set(offset, opcode, operands);
-            return _readInstruction;
+            outInstruction.Set(offset, opcode, operands);
         }
     }
 }
diff --git a/Emux/Gui/MainWindow.xaml.cs b/Emux/Gui/MainWindow.xaml.cs
index 5895f3a..70a9504 100644
--- a/Emux/Gui/MainWindow.xaml.cs
+++ b/Emux/Gui/MainWindow.xaml.cs
@@ -215,10 +215,11 @@ namespace Emux.Gui
                 ;
             DisassemblyView.Items.Clear();
             var disassembler = new Z80Disassembler(_currentDevice.Memory);
-            disassembler.Position = _currentDevice.Cpu.Registers.PC;
-            for (int i = 0; i < 30 && disassembler.Position < 0xFFFF; i ++)
+            var position = _currentDevice.Cpu.Registers.PC;
+            for (int i = 0; i < 30 && position < 0xFFFF; i ++)
             {
-                var instruction = disassembler.ReadNextInstruction();
+                var instruction = new Z80Instruction(0, Z80OpCodes.SingleByteOpCodes[0], new byte[0]);
+                disassembler.ReadInstruction(ref position, instruction);
                 DisassemblyView.Items.Add(new InstructionItem(_currentDevice, instruction));
             }