diff --git a/apps/files_versions/lib/storage.php b/apps/files_versions/lib/storage.php
index ad17668e63..88a4126dab 100644
--- a/apps/files_versions/lib/storage.php
+++ b/apps/files_versions/lib/storage.php
@@ -52,6 +52,10 @@ class Storage {
 	const DEFAULTMAXSIZE=50; // unit: percentage; 50% of available disk space/quota
 	const VERSIONS_ROOT = 'files_versions/';
 
+	const DELETE_TRIGGER_MASTER_REMOVED = 0;
+	const DELETE_TRIGGER_RETENTION_CONSTRAINT = 1;
+	const DELETE_TRIGGER_QUOTA_EXCEEDED = 2;
+
 	// files for which we can remove the versions after the delete operation was successful
 	private static $deletedFiles = array();
 
@@ -210,9 +214,9 @@ class Storage {
 			$versions = self::getVersions($uid, $filename);
 			if (!empty($versions)) {
 				foreach ($versions as $v) {
-					\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $path . $v['version'], 'trigger' => 'master file deleted'));
+					\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $path . $v['version'], 'trigger' => self::DELETE_TRIGGER_MASTER_REMOVED));
 					self::deleteVersion($view, $filename . '.v' . $v['version']);
-					\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $path . $v['version'], 'trigger' => 'master file deleted'));
+					\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $path . $v['version'], 'trigger' => self::DELETE_TRIGGER_MASTER_REMOVED));
 				}
 			}
 		}
@@ -445,9 +449,9 @@ class Storage {
 		$view = new \OC\Files\View('/' . $uid . '/files_versions');
 		if (!empty($toDelete)) {
 			foreach ($toDelete as $version) {
-				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => 'retention constraint'));
+				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => self::DELETE_TRIGGER_RETENTION_CONSTRAINT));
 				self::deleteVersion($view, $version['path'] . '.v' . $version['version']);
-				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => 'retention constraint'));
+				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => self::DELETE_TRIGGER_RETENTION_CONSTRAINT));
 			}
 		}
 	}
@@ -706,9 +710,9 @@ class Storage {
 			}
 
 			foreach($toDelete as $key => $path) {
-				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $path, 'trigger' => 'versions quota exceeded'));
+				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $path, 'trigger' => self::DELETE_TRIGGER_QUOTA_EXCEEDED));
 				self::deleteVersion($versionsFileview, $path);
-				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $path, 'trigger' => 'versions quota exceeded'));
+				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $path, 'trigger' => self::DELETE_TRIGGER_QUOTA_EXCEEDED));
 				unset($allVersions[$key]); // update array with the versions we keep
 				\OCP\Util::writeLog('files_versions', "Expire: " . $path, \OCP\Util::DEBUG);
 			}
@@ -723,9 +727,9 @@ class Storage {
 			reset($allVersions);
 			while ($availableSpace < 0 && $i < $numOfVersions) {
 				$version = current($allVersions);
-				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => 'versions quota exceeded'));
+				\OC_Hook::emit('\OCP\Versions', 'preDelete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => self::DELETE_TRIGGER_QUOTA_EXCEEDED));
 				self::deleteVersion($versionsFileview, $version['path'] . '.v' . $version['version']);
-				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => 'versions quota exceeded'));
+				\OC_Hook::emit('\OCP\Versions', 'delete', array('path' => $version['path'].'.v'.$version['version'], 'trigger' => self::DELETE_TRIGGER_QUOTA_EXCEEDED));
 				\OCP\Util::writeLog('files_versions', 'running out of space! Delete oldest version: ' . $version['path'].'.v'.$version['version'] , \OCP\Util::DEBUG);
 				$versionsSize -= $version['size'];
 				$availableSpace += $version['size'];