diff --git a/koji/auth.py b/koji/auth.py
index c9a4aeed..36b66097 100644
--- a/koji/auth.py
+++ b/koji/auth.py
@@ -369,14 +369,6 @@ class Session(object):
                 proxy_opt = 'ProxyDNs'
             proxy_dns = [dn.strip() for dn in context.opts.get(proxy_opt, '').split(delimiter)]
 
-            # backwards compatible for GSSAPI.
-            # in old way, proxy user whitelist is ProxyDNs.
-            # TODO: this should be removed in future release
-            if authtype == koji.AUTHTYPES['GSSAPI'] and not context.opts.get(
-                    'DisableGSSAPIProxyDNFallback', False):
-                proxy_dns += [dn.strip() for dn in
-                              context.opts.get('ProxyDNs', '').split('|')]
-
             if client_dn in proxy_dns:
                 # the user authorized to login other users
                 username = proxyuser
diff --git a/kojihub/app/hub.conf b/kojihub/app/hub.conf
index 0ea5164d..deca03ec 100644
--- a/kojihub/app/hub.conf
+++ b/kojihub/app/hub.conf
@@ -33,8 +33,6 @@ KojiDir = /mnt/koji
 ## Allowed Kerberos Realms separated by ','.
 ## Default value "*" indicates any Realm is allowed
 # AllowedKrbRealms = *
-## TODO: this option should be removed in future release
-# DisableGSSAPIProxyDNFallback = False
 ## TODO: this option should be turned True in 1.34
 # DisableURLSessions = False
 
diff --git a/kojihub/kojixmlrpc.py b/kojihub/kojixmlrpc.py
index 1881a881..f598d370 100644
--- a/kojihub/kojixmlrpc.py
+++ b/kojihub/kojixmlrpc.py
@@ -445,8 +445,6 @@ def load_config(environ):
         ['ProxyPrincipals', 'string', ''],
         ['HostPrincipalFormat', 'string', None],
         ['AllowedKrbRealms', 'string', '*'],
-        # TODO: this option should be removed in future release
-        ['DisableGSSAPIProxyDNFallback', 'boolean', False],
         # TODO:  this option should be turned True in 1.34
         ['DisableURLSessions', 'boolean', False],
 
@@ -722,10 +720,6 @@ def server_setup(environ):
     try:
         setup_logging1()
         opts = load_config(environ)
-        if opts['DisableGSSAPIProxyDNFallback']:
-            logger.warning(
-                'Hub option DisableGSSAPIProxyDNFallback is deprecated and '
-                'will be removed in 1.29')
         setup_logging2(opts)
         koji.util.setup_rlimits(opts)
         plugins = load_plugins(opts)