diff --git a/src/octoprint/users.py b/src/octoprint/users.py
index 0147329e..c5bb27d6 100644
--- a/src/octoprint/users.py
+++ b/src/octoprint/users.py
@@ -329,7 +329,7 @@ class FilebasedUserManager(UserManager):
 		self._save()
 
 	def getAllUserSettings(self, username):
-		if not username in self._users.key():
+		if not username in self._users.keys():
 			raise UnknownUser(username)
 
 		user = self._users[username]