diff --git a/src/backend/backend.ts b/src/backend/backend.ts
index d47f89b3..747c0188 100644
--- a/src/backend/backend.ts
+++ b/src/backend/backend.ts
@@ -141,29 +141,25 @@ export interface MIError extends Error {
 	readonly source: string;
 }
 export interface MIErrorConstructor {
-	new (message: string, source: string): MIError;
+	new(message: string, source: string): MIError;
 	readonly prototype: MIError;
 }
 
-export const MIError: MIErrorConstructor = <any> class MIError {
-	readonly name: string;
-	readonly message: string;
-	readonly source: string;
+export const MIError: MIErrorConstructor = class MIError {
+	private readonly _message: string;
+	private readonly _source: string;
 	public constructor(message: string, source: string) {
-		Object.defineProperty(this, 'name', {
-			get: () => (this.constructor as any).name,
-		});
-		Object.defineProperty(this, 'message', {
-			get: () => message,
-		});
-		Object.defineProperty(this, 'source', {
-			get: () => source,
-		});
+		this._message = message;
+		this._source = source;
 		Error.captureStackTrace(this, this.constructor);
 	}
 
+	get name() { return this.constructor.name; }
+	get message() { return this._message; }
+	get source() { return this._source; }
+
 	public toString() {
-		return `${this.message} (from ${this.source})`;
+		return `${this.message} (from ${this._source})`;
 	}
 };
 Object.setPrototypeOf(MIError as any, Object.create(Error.prototype));
diff --git a/src/backend/mi2/mi2.ts b/src/backend/mi2/mi2.ts
index 7f2b81e7..fe55b09a 100644
--- a/src/backend/mi2/mi2.ts
+++ b/src/backend/mi2/mi2.ts
@@ -314,14 +314,14 @@ export class MI2 extends EventEmitter implements IBackend {
 		}
 	}
 
-	onOutputStderr(lines) {
-		lines = <string[]> lines.split('\n');
+	onOutputStderr(str: string) {
+		let lines = str.split('\n');
 		lines.forEach(line => {
 			this.log("stderr", line);
 		});
 	}
 
-	onOutputPartial(line) {
+	onOutputPartial(line: string) {
 		if (couldBeOutput(line)) {
 			this.logNoNewLine("stdout", line);
 			return true;
@@ -329,8 +329,8 @@ export class MI2 extends EventEmitter implements IBackend {
 		return false;
 	}
 
-	onOutput(lines) {
-		lines = <string[]> lines.split('\n');
+	onOutput(str: string) {
+		let lines = str.split('\n');
 		lines.forEach(line => {
 			if (couldBeOutput(line)) {
 				if (!gdbMatch.exec(line))
@@ -391,13 +391,13 @@ export class MI2 extends EventEmitter implements IBackend {
 											case "solib-event":
 											case "syscall-entry":
 											case "syscall-return":
-											// TODO: inform the user
+												// TODO: inform the user
 												this.emit("step-end", parsed);
 												break;
 											case "fork":
 											case "vfork":
 											case "exec":
-											// TODO: inform the user, possibly add second inferior
+												// TODO: inform the user, possibly add second inferior
 												this.emit("step-end", parsed);
 												break;
 											case "signal-received":
@@ -410,10 +410,10 @@ export class MI2 extends EventEmitter implements IBackend {
 												this.log("stderr", "Program exited with code " + parsed.record("exit-code"));
 												this.emit("exited-normally", parsed);
 												break;
-												// case "exited-signalled":	// consider handling that explicit possible
-												// 	this.log("stderr", "Program exited because of signal " + parsed.record("signal"));
-												// 	this.emit("stopped", parsed);
-												// 	break;
+											// case "exited-signalled":	// consider handling that explicit possible
+											// 	this.log("stderr", "Program exited because of signal " + parsed.record("signal"));
+											// 	this.emit("stopped", parsed);
+											// 	break;
 
 											default:
 												this.log("console", "Not implemented stop reason (assuming exception): " + reason);
@@ -570,7 +570,7 @@ export class MI2 extends EventEmitter implements IBackend {
 		return Promise.all(promisses);
 	}
 
-	setBreakPointCondition(bkptNum, condition): Thenable<any> {
+	setBreakPointCondition(bkptNum: number, condition: string): Thenable<any> {
 		if (trace)
 			this.log("stderr", "setBreakPointCondition");
 		return this.sendCommand("break-condition " + bkptNum + " " + condition);
@@ -802,7 +802,7 @@ export class MI2 extends EventEmitter implements IBackend {
 		const ret: RegisterValue[] = nodes.map(node => {
 			const index = parseInt(MINode.valueOf(node, "number"));
 			const value = MINode.valueOf(node, "value");
-			return {index: index, value: value};
+			return { index: index, value: value };
 		});
 		return ret;
 	}
diff --git a/src/backend/mi2/mi2lldb.ts b/src/backend/mi2/mi2lldb.ts
index 44999144..e04f118c 100644
--- a/src/backend/mi2/mi2lldb.ts
+++ b/src/backend/mi2/mi2lldb.ts
@@ -4,7 +4,7 @@ import * as ChildProcess from "child_process";
 import * as path from "path";
 
 export class MI2_LLDB extends MI2 {
-	protected initCommands(target: string, cwd: string, attach: boolean = false) {
+	protected override initCommands(target: string, cwd: string, attach: boolean = false) {
 		// We need to account for the possibility of the path type used by the debugger being different
 		// than the path type where the extension is running (e.g., SSH from Linux to Windows machine).
 		// Since the CWD is expected to be an absolute path in the debugger's environment, we can test
@@ -35,7 +35,7 @@ export class MI2_LLDB extends MI2 {
 		return cmds;
 	}
 
-	attach(cwd: string, executable: string, target: string, autorun: string[]): Thenable<any> {
+	override attach(cwd: string, executable: string, target: string, autorun: string[]): Thenable<any> {
 		return new Promise((resolve, reject) => {
 			const args = this.preargs.concat(this.extraargs || []);
 			this.process = ChildProcess.spawn(this.application, args, { cwd: cwd, env: this.procEnv });
@@ -54,11 +54,11 @@ export class MI2_LLDB extends MI2 {
 		});
 	}
 
-	setBreakPointCondition(bkptNum, condition): Thenable<any> {
+	override setBreakPointCondition(bkptNum: number, condition: string): Thenable<any> {
 		return this.sendCommand("break-condition " + bkptNum + " \"" + escape(condition) + "\" 1");
 	}
 
-	goto(filename: string, line: number): Thenable<Boolean> {
+	override goto(filename: string, line: number): Thenable<Boolean> {
 		return new Promise((resolve, reject) => {
 			// LLDB parses the file differently than GDB...
 			// GDB doesn't allow quoting only the file but only the whole argument