diff --git a/apps/dav/lib/Connector/Sabre/File.php b/apps/dav/lib/Connector/Sabre/File.php
index 45b31c2e11..bbd6717d94 100644
--- a/apps/dav/lib/Connector/Sabre/File.php
+++ b/apps/dav/lib/Connector/Sabre/File.php
@@ -51,6 +51,7 @@ use OCP\Files\InvalidContentException;
 use OCP\Files\InvalidPathException;
 use OCP\Files\LockNotAcquiredException;
 use OCP\Files\NotPermittedException;
+use OCP\Files\Storage;
 use OCP\Files\StorageNotAvailableException;
 use OCP\Lock\ILockingProvider;
 use OCP\Lock\LockedException;
@@ -135,8 +136,9 @@ class File extends Node implements IFile {
 			}
 		}
 
+		/** @var Storage $partStorage */
 		list($partStorage) = $this->fileView->resolvePath($this->path);
-		$needsPartFile = $this->needsPartFile($partStorage) && (strlen($this->path) > 1);
+		$needsPartFile = $partStorage->needsPartFile() && (strlen($this->path) > 1);
 
 		if ($needsPartFile) {
 			// mark file as partial while uploading (ignored by the scanner)
@@ -443,8 +445,9 @@ class File extends Node implements IFile {
 		}
 
 		if ($chunk_handler->isComplete()) {
+			/** @var Storage $storage */
 			list($storage,) = $this->fileView->resolvePath($path);
-			$needsPartFile = $this->needsPartFile($storage);
+			$needsPartFile = $storage->needsPartFile();
 			$partFile = null;
 
 			$targetPath = $path . '/' . $info['name'];
@@ -529,21 +532,6 @@ class File extends Node implements IFile {
 		return null;
 	}
 
-	/**
-	 * Returns whether a part file is needed for the given storage
-	 * or whether the file can be assembled/uploaded directly on the
-	 * target storage.
-	 *
-	 * @param \OCP\Files\Storage $storage
-	 * @return bool true if the storage needs part file handling
-	 */
-	private function needsPartFile($storage) {
-		// TODO: in the future use ChunkHandler provided by storage
-		return !$storage->instanceOfStorage('OCA\Files_Sharing\External\Storage') &&
-			!$storage->instanceOfStorage('OC\Files\Storage\OwnCloud') &&
-			$storage->needsPartFile();
-	}
-
 	/**
 	 * Convert the given exception to a SabreException instance
 	 *
diff --git a/apps/files_external/lib/Lib/Storage/OwnCloud.php b/apps/files_external/lib/Lib/Storage/OwnCloud.php
index d56e6b6614..3ee2b70ef2 100644
--- a/apps/files_external/lib/Lib/Storage/OwnCloud.php
+++ b/apps/files_external/lib/Lib/Storage/OwnCloud.php
@@ -73,4 +73,8 @@ class OwnCloud extends \OC\Files\Storage\DAV{
 
 		parent::__construct($params);
 	}
+
+	public function needsPartFile() {
+		return false;
+	}
 }
diff --git a/apps/files_sharing/lib/External/Storage.php b/apps/files_sharing/lib/External/Storage.php
index 638f82f702..a631a029ab 100644
--- a/apps/files_sharing/lib/External/Storage.php
+++ b/apps/files_sharing/lib/External/Storage.php
@@ -366,4 +366,7 @@ class Storage extends DAV implements ISharedStorage {
 		return $permissions;
 	}
 
+	public function needsPartFile() {
+		return false;
+	}
 }