diff --git a/src/activateMockDebug.ts b/src/activateMockDebug.ts
index 0e83b96..f451e44 100644
--- a/src/activateMockDebug.ts
+++ b/src/activateMockDebug.ts
@@ -183,7 +183,7 @@ class MockConfigurationProvider implements vscode.DebugConfigurationProvider {
 }
 
 export const workspaceFileAccessor: FileAccessor = {
-	isWindows: false,
+	isWindows: typeof process !== 'undefined' && process.platform === 'win32',
 	async readFile(path: string): Promise<Uint8Array> {
 		let uri: vscode.Uri;
 		try {
diff --git a/src/mockDebug.ts b/src/mockDebug.ts
index 5bfc23d..b02f49e 100644
--- a/src/mockDebug.ts
+++ b/src/mockDebug.ts
@@ -752,22 +752,23 @@ export class MockDebugSession extends LoggingDebugSession {
 	}
 
 	protected disassembleRequest(response: DebugProtocol.DisassembleResponse, args: DebugProtocol.DisassembleArguments) {
-
-		const baseAddress = parseInt(args.memoryReference);
+		const memoryInt = args.memoryReference.slice(3);
+		const baseAddress = parseInt(memoryInt);
 		const offset = args.instructionOffset || 0;
 		const count = args.instructionCount;
 
-		const isHex = args.memoryReference.startsWith('0x');
-		const pad = isHex ? args.memoryReference.length-2 : args.memoryReference.length;
+		const isHex = memoryInt.startsWith('0x');
+		const pad = isHex ? memoryInt.length-2 : memoryInt.length;
 
 		const loc = this.createSource(this._runtime.sourceFile);
 
 		let lastLine = -1;
 
 		const instructions = this._runtime.disassemble(baseAddress+offset, count).map(instruction => {
-			const address = instruction.address.toString(isHex ? 16 : 10).padStart(pad, '0');
+			let address = Math.abs(instruction.address).toString(isHex ? 16 : 10).padStart(pad, '0');
+			const sign = instruction.address < 0 ? '-' : '';
 			const instr : DebugProtocol.DisassembledInstruction = {
-				address: isHex ? `0x${address}` : `${address}`,
+				address: sign + (isHex ? `0x${address}` : `${address}`),
 				instruction: instruction.instruction
 			};
 			// if instruction's source starts on a new line add the source to instruction
@@ -792,7 +793,7 @@ export class MockDebugSession extends LoggingDebugSession {
 
 		// set instruction breakpoints
 		const breakpoints = args.breakpoints.map(ibp => {
-			const address = parseInt(ibp.instructionReference);
+			const address = parseInt(ibp.instructionReference.slice(3));
 			const offset = ibp.offset || 0;
 			return <DebugProtocol.Breakpoint>{
 				verified: this._runtime.setInstructionBreakpoint(address + offset)
@@ -897,7 +898,7 @@ export class MockDebugSession extends LoggingDebugSession {
 	}
 
 	private formatAddress(x: number, pad = 8) {
-		return this._addressesInHex ? '0x' + x.toString(16).padStart(8, '0') : x.toString(10);
+		return 'mem' + (this._addressesInHex ? '0x' + x.toString(16).padStart(8, '0') : x.toString(10));
 	}
 
 	private formatNumber(x: number) {
diff --git a/src/mockRuntime.ts b/src/mockRuntime.ts
index 1bebfe7..87858a6 100644
--- a/src/mockRuntime.ts
+++ b/src/mockRuntime.ts
@@ -311,7 +311,7 @@ export class MockRuntime extends EventEmitter {
 				file: this._sourceFile,
 				line: this.currentLine,
 				column: column, // words[i].index
-				instruction: instruction
+				instruction: instruction ? instruction + i : 0
 			};
 
 			frames.push(stackFrame);