diff --git a/src/vs/vscode.d.ts b/src/vs/vscode.d.ts
index 5f60c994fad..ae7b4852481 100644
--- a/src/vs/vscode.d.ts
+++ b/src/vs/vscode.d.ts
@@ -209,14 +209,16 @@ declare module 'vscode' {
 		/**
 		 * Get a word-range at the given position. By default words are defined by
 		 * common separators, like space, -, _, etc. In addition, per languge custom
-		 * [word definitions](#LanguageConfiguration.wordPattern) can be defined.
+		 * [word definitions](#LanguageConfiguration.wordPattern) can be defined. It
+		 * is also possible to provide a custom regular expression.
 		 *
 		 * The position will be [adjusted](#TextDocument.validatePosition).
 		 *
 		 * @param position A position.
+		 * @param regex Optional regular expression that describes what a word is.
 		 * @return A range spanning a word, or `undefined`.
 		 */
-		getWordRangeAtPosition(position: Position): Range;
+		getWordRangeAtPosition(position: Position, regex?: RegExp): Range;
 
 		/**
 		 * Ensure a range is completely contained in this document.
diff --git a/src/vs/workbench/api/node/extHostDocuments.ts b/src/vs/workbench/api/node/extHostDocuments.ts
index 8f7b18db3ff..7b9eaf556da 100644
--- a/src/vs/workbench/api/node/extHostDocuments.ts
+++ b/src/vs/workbench/api/node/extHostDocuments.ts
@@ -5,6 +5,7 @@
 'use strict';
 
 import { onUnexpectedError } from 'vs/base/common/errors';
+import { regExpLeadsToEndlessLoop } from 'vs/base/common/strings';
 import * as editorCommon from 'vs/editor/common/editorCommon';
 import { MirrorModel2 } from 'vs/editor/common/model/mirrorModel2';
 import { IThreadService } from 'vs/workbench/services/thread/common/threadService';
@@ -262,7 +263,7 @@ export class ExtHostDocumentData extends MirrorModel2 {
 				positionAt(offset) { return data.positionAt(offset); },
 				validateRange(ran) { return data.validateRange(ran); },
 				validatePosition(pos) { return data.validatePosition(pos); },
-				getWordRangeAtPosition(pos) { return data.getWordRangeAtPosition(pos); }
+				getWordRangeAtPosition(pos, regexp?) { return data.getWordRangeAtPosition(pos, regexp); }
 			};
 		}
 		return this._document;
@@ -410,12 +411,14 @@ export class ExtHostDocumentData extends MirrorModel2 {
 		return new Position(line, character);
 	}
 
-	getWordRangeAtPosition(_position: vscode.Position): vscode.Range {
+	getWordRangeAtPosition(_position: vscode.Position, regexp?: RegExp): vscode.Range {
 		let position = this.validatePosition(_position);
-
+		if (!regexp || regExpLeadsToEndlessLoop(regexp)) {
+			regexp = getWordDefinitionFor(this._languageId);
+		}
 		let wordAtText = getWordAtText(
 			position.character + 1,
-			ensureValidWordDefinition(getWordDefinitionFor(this._languageId)),
+			ensureValidWordDefinition(regexp),
 			this._lines[position.line],
 			0
 		);
diff --git a/src/vs/workbench/test/node/api/extHostDocuments.test.ts b/src/vs/workbench/test/node/api/extHostDocuments.test.ts
index 93c11669a18..b20a73865ef 100644
--- a/src/vs/workbench/test/node/api/extHostDocuments.test.ts
+++ b/src/vs/workbench/test/node/api/extHostDocuments.test.ts
@@ -204,6 +204,39 @@ suite('ExtHostDocument', () => {
 		assertPositionAt(99, 3, 29);
 		assertPositionAt(Number.MAX_VALUE, 3, 29);
 	});
+
+	test('getWordRangeAtPosition', function () {
+		data = new ExtHostDocumentData(undefined, URI.file(''), [
+			'aaaa bbbb cccc abc'
+		], '\n', 'text', 1, false);
+
+		let range = data.getWordRangeAtPosition(new Position(0, 2));
+		assert.equal(range.start.line, 0);
+		assert.equal(range.start.character, 0);
+		assert.equal(range.end.line, 0);
+		assert.equal(range.end.character, 4);
+
+		range = data.getWordRangeAtPosition(new Position(0, 2), /.*/);
+		assert.equal(range.start.line, 0);
+		assert.equal(range.start.character, 0);
+		assert.equal(range.end.line, 0);
+		assert.equal(range.end.character, 4);
+
+		range = data.getWordRangeAtPosition(new Position(0, 2), /a+.+?c/);
+		assert.equal(range.start.line, 0);
+		assert.equal(range.start.character, 0);
+		assert.equal(range.end.line, 0);
+		assert.equal(range.end.character, 11);
+
+		range = data.getWordRangeAtPosition(new Position(0, 17), /a+.+?c/);
+		assert.equal(range.start.line, 0);
+		assert.equal(range.start.character, 15);
+		assert.equal(range.end.line, 0);
+		assert.equal(range.end.character, 18);
+
+		range = data.getWordRangeAtPosition(new Position(0, 11), /yy/);
+		assert.equal(range, undefined);
+	});
 });
 
 enum AssertDocumentLineMappingDirection {
@@ -372,4 +405,4 @@ suite('ExtHostDocument updates line mapping', () => {
 			'and finished with the fourth.',
 		], [createChangeEvent(new CodeEditorRange(1, 1, 1, 1), '', '\n')]);
 	});
-});
\ No newline at end of file
+});