diff --git a/lib/private/Files/Stream/Encryption.php b/lib/private/Files/Stream/Encryption.php
index fc75ead1e45..014f752a162 100644
--- a/lib/private/Files/Stream/Encryption.php
+++ b/lib/private/Files/Stream/Encryption.php
@@ -524,7 +524,7 @@ class Encryption extends Wrapper {
 	/**
 	 * write header at beginning of encrypted file
 	 *
-	 * @return integer
+	 * @return int|false
 	 * @throws EncryptionHeaderKeyExistsException if header key is already in use
 	 */
 	protected function writeHeader() {