diff --git a/src/vs/base/common/errors.ts b/src/vs/base/common/errors.ts
index 0bdcb986ad6..24ac4ae2794 100644
--- a/src/vs/base/common/errors.ts
+++ b/src/vs/base/common/errors.ts
@@ -380,8 +380,10 @@ export function illegalState(name?: string): Error {
 	}
 }
 
-export function readonly(): Error {
-	return new Error('readonly property cannot be changed');
+export function readonly(name?: string): Error {
+	return name
+		? new Error(`readonly property '${name} cannot be changed'`)
+		: new Error('readonly property cannot be changed');
 }
 
 export function loaderError(err: Error): Error {
diff --git a/src/vs/workbench/api/node/extHostEditors.ts b/src/vs/workbench/api/node/extHostEditors.ts
index a20d98d4bb6..9e33cd99f3f 100644
--- a/src/vs/workbench/api/node/extHostEditors.ts
+++ b/src/vs/workbench/api/node/extHostEditors.ts
@@ -5,6 +5,7 @@
 'use strict';
 
 import URI from 'vs/base/common/uri';
+import {readonly, illegalArgument} from 'vs/base/common/errors';
 import {IdGenerator} from 'vs/base/common/idGenerator';
 import Event, {Emitter} from 'vs/base/common/event';
 import {IDisposable, dispose} from 'vs/base/common/lifecycle';
@@ -268,24 +269,13 @@ export class TextEditorEdit {
 
 	setEndOfLine(endOfLine:EndOfLine): void {
 		if (endOfLine !== EndOfLine.LF && endOfLine !== EndOfLine.CRLF) {
-			throw illegalArg('endOfLine');
+			throw illegalArgument('endOfLine');
 		}
 
 		this._setEndOfLine = endOfLine;
 	}
 }
 
-function readonly(name: string, alt?: string) {
-	let message = `The property '${name}' is readonly.`;
-	if (alt) {
-		message += ` Use '${alt}' instead.`;
-	}
-	return new Error(message);
-}
-
-function illegalArg(name: string) {
-	return new Error(`illgeal argument '${name}'`);
-}
 
 function deprecated(name: string, message: string = 'Refer to the documentation for further details.') {
 	return (target: Object, key: string, descriptor: TypedPropertyDescriptor<any>) => {
@@ -379,7 +369,7 @@ class ExtHostTextEditor implements vscode.TextEditor {
 
 	set selection(value: Selection) {
 		if (!(value instanceof Selection)) {
-			throw illegalArg('selection');
+			throw illegalArgument('selection');
 		}
 		this._selections = [value];
 		this._trySetSelection(true);
@@ -391,7 +381,7 @@ class ExtHostTextEditor implements vscode.TextEditor {
 
 	set selections(value: Selection[]) {
 		if (!Array.isArray(value) || value.some(a => !(a instanceof Selection))) {
-			throw illegalArg('selections');
+			throw illegalArgument('selections');
 		}
 		this._selections = value;
 		this._trySetSelection(true);