diff --git a/lib/Folder/FolderManager.php b/lib/Folder/FolderManager.php
index 7ee5a1e96..5d83fd72b 100644
--- a/lib/Folder/FolderManager.php
+++ b/lib/Folder/FolderManager.php
@@ -86,7 +86,7 @@ private function getAllApplicable() {
 
 	/**
 	 * @param string $groupId
-	 * @return array [$mountPoint => $permissions]
+	 * @return array[]
 	 */
 	public function getFoldersForGroup($groupId) {
 		$query = $this->connection->getQueryBuilder();
@@ -101,7 +101,15 @@ public function getFoldersForGroup($groupId) {
 			)
 			->where($query->expr()->eq('a.group_id', $query->createNamedParameter($groupId)));
 
-		return $query->execute()->fetchAll();
+		$result = $query->execute()->fetchAll();
+		return array_map(function ($folder) {
+			return [
+				'folder_id' => (int)$folder['folder_id'],
+				'mount_point' => $folder['mount_point'],
+				'permissions' => (int)$folder['permissions'],
+				'quota' => (int)$folder['quota'],
+			];
+		}, $result);
 	}
 
 	public function createFolder($mountPoint) {
diff --git a/lib/Mount/MountProvider.php b/lib/Mount/MountProvider.php
index d01bedf9f..df9135914 100644
--- a/lib/Mount/MountProvider.php
+++ b/lib/Mount/MountProvider.php
@@ -57,12 +57,28 @@ public function __construct(IGroupManager $groupProvider, FolderManager $folderM
 		$this->rootProvider = $rootProvider;
 	}
 
-	public function getMountsForUser(IUser $user, IStorageFactory $loader) {
+	public function getFoldersForUser(IUser $user) {
 		$groups = $this->groupProvider->getUserGroupIds($user);
 		$folders = array_reduce($groups, function ($folders, $groupId) {
 			return array_merge($folders, $this->folderManager->getFoldersForGroup($groupId));
 		}, []);
 
+		$mergedFolders = [];
+		foreach ($folders as $folder) {
+			$id = $folder['folder_id'];
+			if (isset($mergedFolders[$id])) {
+				$mergedFolders[$id]['permissions'] |= $folder['permissions'];
+			} else {
+				$mergedFolders[$id] = $folder;
+			}
+		}
+
+		return array_values($mergedFolders);
+	}
+
+	public function getMountsForUser(IUser $user, IStorageFactory $loader) {
+		$folders = $this->getFoldersForUser($user);
+
 		return array_map(function ($folder) use ($user, $loader) {
 			return $this->getMount($folder['folder_id'], '/' . $user->getUID() . '/files/' . $folder['mount_point'], $folder['permissions'], $folder['quota'], $loader);
 		}, $folders);
diff --git a/tests/Folder/FolderManagerTest.php b/tests/Folder/FolderManagerTest.php
index 955d198f8..af1295321 100644
--- a/tests/Folder/FolderManagerTest.php
+++ b/tests/Folder/FolderManagerTest.php
@@ -147,4 +147,17 @@ public function testRenameFolder() {
 			['mount_point' => 'other', 'groups' => []],
 		]);
 	}
+
+	public function testGetFoldersForGroup() {
+		$folderId1 = $this->manager->createFolder('foo');
+		$this->manager->addApplicableGroup($folderId1, 'g1');
+		$this->manager->addApplicableGroup($folderId1, 'g2');
+		$this->manager->setGroupPermissions($folderId1, 'g1', 2);
+
+		$folders = $this->manager->getFoldersForGroup('g1');
+		$this->assertCount(1, $folders);
+		$folder = $folders[0];
+		$this->assertEquals('foo', $folder['mount_point']);
+		$this->assertEquals(2, $folder['permissions']);
+	}
 }
diff --git a/tests/Mount/MountProviderTest.php b/tests/Mount/MountProviderTest.php
new file mode 100644
index 000000000..754f4ffac
--- /dev/null
+++ b/tests/Mount/MountProviderTest.php
@@ -0,0 +1,141 @@
+<?php
+/**
+ * @copyright Copyright (c) 2017 Robin Appelman <robin@icewind.nl>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\GroupFolders\Tests\Mount;
+
+use OC\User\User;
+use OCA\GroupFolders\Folder\FolderManager;
+use OCA\GroupFolders\Mount\MountProvider;
+use OCP\Files\Folder;
+use OCP\Files\Storage\IStorageFactory;
+use OCP\IGroupManager;
+use OCP\IUser;
+use Test\TestCase;
+use Test\Traits\UserTrait;
+
+class MountProviderTest extends TestCase {
+	/** @var IGroupManager|\PHPUnit_Framework_MockObject_MockObject */
+	private $groupManager;
+	/** @var FolderManager|\PHPUnit_Framework_MockObject_MockObject */
+	private $folderManager;
+	/** @var Folder|\PHPUnit_Framework_MockObject_MockObject */
+	private $rootFolder;
+	/** @var IStorageFactory|\PHPUnit_Framework_MockObject_MockObject */
+	private $loader;
+	/** @var MountProvider */
+	private $mountProvider;
+
+	protected function setUp() {
+		parent::setUp();
+
+		$this->groupManager = $this->createMock(IGroupManager::class);
+		$this->folderManager = $this->createMock(FolderManager::class);
+		$this->rootFolder = $this->createMock(Folder::class);
+		$this->loader = $this->createMock(IStorageFactory::class);
+
+		$this->rootFolder->expects($this->any())
+			->method('get')
+			->willReturn($this->rootFolder);
+
+		$this->mountProvider = new MountProvider($this->groupManager, $this->folderManager, function () {
+			return $this->rootFolder;
+		});
+	}
+
+	/**
+	 * @param string[] $groups
+	 * @return \PHPUnit_Framework_MockObject_MockObject|IUser
+	 */
+	protected function getUser($groups = []) {
+		$user = $this->createMock(IUser::class);
+		$this->groupManager->expects($this->any())
+			->method('getUserGroupIds')
+			->willReturn($groups);
+
+		return $user;
+	}
+
+	public function testGetFoldersForUserEmpty() {
+		$folders = $this->mountProvider->getFoldersForUser($this->getUser());
+		$this->assertEquals([], $folders);
+	}
+
+	public function testGetFoldersForUserSimple() {
+		$folder = [
+			[
+				'folder_id' => 1,
+				'mount_point' => 'foo',
+				'permissions' => 31,
+				'quota' => -3
+			]
+		];
+
+		$this->folderManager->expects($this->once())
+			->method('getFoldersForGroup')
+			->willReturn($folder);
+
+		$folders = $this->mountProvider->getFoldersForUser($this->getUser(['g1']));
+		$this->assertEquals($folder, $folders);
+	}
+
+	public function testGetFoldersForUserMerge() {
+		$folder1 = [
+			[
+				'folder_id' => 1,
+				'mount_point' => 'foo',
+				'permissions' => 3,
+				'quota' => 1000
+			]
+		];
+		$folder2 = [
+			[
+				'folder_id' => 1,
+				'mount_point' => 'foo',
+				'permissions' => 8,
+				'quota' => 1000
+			]
+		];
+
+		$this->folderManager->expects($this->any())
+			->method('getFoldersForGroup')
+			->willReturnCallback(function ($group) use ($folder1, $folder2) {
+				switch ($group) {
+					case 'g1':
+						return $folder1;
+					case 'g2':
+						return $folder2;
+					default:
+						return [];
+				}
+			});
+
+		$folders = $this->mountProvider->getFoldersForUser($this->getUser(['g1', 'g2', 'g3']));
+		$this->assertEquals([
+			[
+				'folder_id' => 1,
+				'mount_point' => 'foo',
+				'permissions' => 11,
+				'quota' => 1000
+			]
+		], $folders);
+	}
+}
+