diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 828af4c..5ec78e3 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -73,9 +73,8 @@ line.
     in the Gerrit web interface.
 
   **auth-type**
-    Authentication type required by the Gerrit server. Can be 'basic'
-    or 'digest'. Defaults to 'digest' if not set or set to an
-    unexpected value.
+    Authentication type required by the Gerrit server. Can be 'basic',
+    'digest', or 'form'. Defaults to 'digest'.
 
   **git-root (required)**
     A location where Gertty should store its git repositories.  These
diff --git a/examples/reference-gertty.yaml b/examples/reference-gertty.yaml
index 4eb77c3..fd4c21e 100644
--- a/examples/reference-gertty.yaml
+++ b/examples/reference-gertty.yaml
@@ -23,8 +23,8 @@ servers:
 #    username: CHANGEME
 # Your password in Gerrit (Settings -> HTTP Password). [required]
 #    password: CHANGEME
-# Authentication type required by the Gerrit server. Can be 'basic', 'digest' or
-# 'form'. Defaults to 'digest' if not set or set to an unexpected value.
+# Authentication type required by the Gerrit server. Can be 'basic',
+# 'digest', or 'form'. Defaults to 'digest'.
 #    auth-type: digest
 # A location where Gertty should store its git repositories.  These
 # can be the same git repositories where you do your own work --
diff --git a/gertty/config.py b/gertty/config.py
index 79c22dc..dce9a6c 100644
--- a/gertty/config.py
+++ b/gertty/config.py
@@ -49,7 +49,7 @@ class ConfigSchema(object):
               'git-url': str,
               'log-file': str,
               'socket': str,
-              'auth-type': str,
+              'auth-type': v.Any('basic', 'digest', 'form'),
               }
 
     servers = [server]
@@ -165,9 +165,6 @@ class Config(object):
                     "Permissions are: {}".format(self.path, oct(mode)))
                 exit(1)
         self.auth_type = server.get('auth-type', 'digest')
-        auth_types = ['digest', 'basic', 'form']
-        if self.auth_type not in auth_types:
-            self.auth_type = 'digest'
         self.verify_ssl = server.get('verify-ssl', True)
         if not self.verify_ssl:
             os.environ['GIT_SSL_NO_VERIFY']='true'