diff --git a/extensions/git/src/contentProvider.ts b/extensions/git/src/contentProvider.ts
index d7bd26dffc2..9ab283dcd1e 100644
--- a/extensions/git/src/contentProvider.ts
+++ b/extensions/git/src/contentProvider.ts
@@ -9,7 +9,7 @@ import { workspace, Uri, Disposable, Event, EventEmitter, window } from 'vscode'
 import { debounce, throttle } from './decorators';
 import { fromGitUri, toGitUri } from './uri';
 import { Model, ModelChangeEvent, OriginalResourceChangeEvent } from './model';
-import { filterEvent, eventToPromise } from './util';
+import { filterEvent, eventToPromise, isDescendant } from './util';
 
 interface CacheRow {
 	uri: Uri;
@@ -72,7 +72,7 @@ export class GitContentProvider {
 			const fsPath = uri.fsPath;
 
 			for (const root of this.changedRepositoryRoots) {
-				if (fsPath.startsWith(root)) {
+				if (isDescendant(root, fsPath)) {
 					this._onDidChange.fire(uri);
 					return;
 				}
diff --git a/extensions/git/src/model.ts b/extensions/git/src/model.ts
index 00be3fd3556..a28d386c38b 100644
--- a/extensions/git/src/model.ts
+++ b/extensions/git/src/model.ts
@@ -8,7 +8,7 @@
 import { workspace, WorkspaceFoldersChangeEvent, Uri, window, Event, EventEmitter, QuickPickItem, Disposable, SourceControl, SourceControlResourceGroup, TextEditor, Memento, ConfigurationChangeEvent } from 'vscode';
 import { Repository, RepositoryState } from './repository';
 import { memoize, sequentialize, debounce } from './decorators';
-import { dispose, anyEvent, filterEvent, IDisposable } from './util';
+import { dispose, anyEvent, filterEvent, IDisposable, isDescendant } from './util';
 import { Git, GitErrorCodes } from './git';
 import * as path from 'path';
 import * as fs from 'fs';
@@ -44,14 +44,6 @@ interface OpenRepository extends Disposable {
 	repository: Repository;
 }
 
-function isParent(parent: string, child: string): boolean {
-	if (parent.charAt(parent.length - 1) !== path.sep) {
-		parent += path.sep;
-	}
-
-	return child.startsWith(parent);
-}
-
 export class Model {
 
 	private _onDidOpenRepository = new EventEmitter<Repository>();
@@ -136,7 +128,7 @@ export class Model {
 			.map(folder => this.getOpenRepository(folder.uri))
 			.filter(r => !!r)
 			.filter(r => !activeRepositories.has(r!.repository))
-			.filter(r => !(workspace.workspaceFolders || []).some(f => isParent(f.uri.fsPath, r!.repository.root))) as OpenRepository[];
+			.filter(r => !(workspace.workspaceFolders || []).some(f => isDescendant(f.uri.fsPath, r!.repository.root))) as OpenRepository[];
 
 		possibleRepositoryFolders.forEach(p => this.tryOpenRepository(p.uri.fsPath));
 		openRepositoriesToDispose.forEach(r => r.dispose());
@@ -285,7 +277,7 @@ export class Model {
 			for (const liveRepository of this.openRepositories) {
 				const relativePath = path.relative(liveRepository.repository.root, resourcePath);
 
-				if (!/^\.\./.test(relativePath)) {
+				if (isDescendant(liveRepository.repository.root, resourcePath)) {
 					return liveRepository;
 				}
 			}
diff --git a/extensions/git/src/repository.ts b/extensions/git/src/repository.ts
index 73242e60c0f..c400a818d9d 100644
--- a/extensions/git/src/repository.ts
+++ b/extensions/git/src/repository.ts
@@ -7,7 +7,7 @@
 
 import { Uri, Command, EventEmitter, Event, scm, SourceControl, SourceControlInputBox, SourceControlResourceGroup, SourceControlResourceState, SourceControlResourceDecorations, Disposable, ProgressLocation, window, workspace, WorkspaceEdit, ThemeColor, DecorationData, Memento } from 'vscode';
 import { Repository as BaseRepository, Ref, Branch, Remote, Commit, GitErrorCodes, Stash, RefType, GitError } from './git';
-import { anyEvent, filterEvent, eventToPromise, dispose, find } from './util';
+import { anyEvent, filterEvent, eventToPromise, dispose, find, isDescendant } from './util';
 import { memoize, throttle, debounce } from './decorators';
 import { toGitUri } from './uri';
 import { AutoFetcher } from './autofetch';
@@ -473,7 +473,7 @@ export class Repository implements Disposable {
 		this.disposables.push(fsWatcher);
 
 		const onWorkspaceChange = anyEvent(fsWatcher.onDidChange, fsWatcher.onDidCreate, fsWatcher.onDidDelete);
-		const onRepositoryChange = filterEvent(onWorkspaceChange, uri => !/^\.\./.test(path.relative(repository.root, uri.fsPath)));
+		const onRepositoryChange = filterEvent(onWorkspaceChange, uri => isDescendant(repository.root, uri.fsPath));
 		const onRelevantRepositoryChange = filterEvent(onRepositoryChange, uri => !/\/\.git\/index\.lock$/.test(uri.path));
 		onRelevantRepositoryChange(this.onFSChange, this, this.disposables);
 
@@ -760,7 +760,8 @@ export class Repository implements Disposable {
 		return this.run(Operation.CheckIgnore, () => {
 			return new Promise<Set<string>>((resolve, reject) => {
 
-				filePaths = filePaths.filter(filePath => !path.relative(this.root, filePath).startsWith('..'));
+				filePaths = filePaths
+					.filter(filePath => isDescendant(this.root, filePath));
 
 				if (filePaths.length === 0) {
 					// nothing left
diff --git a/extensions/git/src/util.ts b/extensions/git/src/util.ts
index ef13e9de13c..6831fea9428 100644
--- a/extensions/git/src/util.ts
+++ b/extensions/git/src/util.ts
@@ -6,7 +6,7 @@
 'use strict';
 
 import { Event } from 'vscode';
-import { dirname } from 'path';
+import { dirname, sep } from 'path';
 import { Readable } from 'stream';
 import * as fs from 'fs';
 import * as byline from 'byline';
@@ -273,4 +273,16 @@ export function detectUnicodeEncoding(buffer: Buffer): Encoding | null {
 	}
 
 	return null;
-}
\ No newline at end of file
+}
+
+export function isDescendant(parent: string, descendant: string): boolean {
+	if (parent === descendant) {
+		return true;
+	}
+
+	if (parent.charAt(parent.length - 1) !== sep) {
+		parent += sep;
+	}
+
+	return descendant.startsWith(parent);
+}