diff --git a/Core/CPU.h b/Core/CPU.h
index eca49264..d8c42a06 100644
--- a/Core/CPU.h
+++ b/Core/CPU.h
@@ -90,7 +90,7 @@ private:
 
 	void DummyRead()
 	{
-		MemoryRead(_state.PC, MemoryOperationType::ExecOperand);
+		MemoryRead(_state.PC, MemoryOperationType::Read);
 	}
 
 	uint8_t ReadByte()
diff --git a/Core/Disassembler.cpp b/Core/Disassembler.cpp
index a82c7214..af045fa4 100644
--- a/Core/Disassembler.cpp
+++ b/Core/Disassembler.cpp
@@ -104,18 +104,21 @@ uint32_t Disassembler::BuildCache(uint32_t absoluteAddr, uint16_t memoryAddr)
 		}
 		return memoryAddr;
 	} else {
-		while(!_disassembleCache[absoluteAddr]) {
-			shared_ptr<DisassemblyInfo> disInfo(new DisassemblyInfo(&_prgROM[absoluteAddr]));
-			_disassembleCache[absoluteAddr] = disInfo;
+		if(!_disassembleCache[absoluteAddr]) {
+			while(absoluteAddr < _prgSize && !_disassembleCache[absoluteAddr]) {
+				shared_ptr<DisassemblyInfo> disInfo(new DisassemblyInfo(&_prgROM[absoluteAddr]));
+				_disassembleCache[absoluteAddr] = disInfo;
 
-			uint8_t opCode = _prgROM[absoluteAddr];
-			if(opCode == 0x10 || opCode == 0x20 || opCode == 0x30 || opCode == 0x40 || opCode == 0x50 || opCode == 0x60 || opCode == 0x70 || opCode == 0x90 || opCode == 0xB0 || opCode == 0xD0 || opCode == 0xF0 || opCode == 0x4C || opCode == 0x6C) {
-				//Hit a jump/return instruction, can't assume that what follows is actual code, stop disassembling
-				break;
+				uint8_t opCode = _prgROM[absoluteAddr];
+				absoluteAddr += disInfo->GetSize();
+				if(opCode == 0x10 || opCode == 0x20 || opCode == 0x30 || opCode == 0x40 || opCode == 0x50 || opCode == 0x60 || opCode == 0x70 || opCode == 0x90 || opCode == 0xB0 || opCode == 0xD0 || opCode == 0xF0 || opCode == 0x4C || opCode == 0x6C) {
+					//Hit a jump/return instruction, can't assume that what follows is actual code, stop disassembling
+					break;
+				}
 			}
-			absoluteAddr += disInfo->GetSize();
+		} else {
+			absoluteAddr += _disassembleCache[absoluteAddr]->GetSize();
 		}
-		absoluteAddr += _disassembleCache[absoluteAddr]->GetSize();
 		return absoluteAddr;
 	}
 }