diff --git a/kong/plugins/basic-auth/access.lua b/kong/plugins/basic-auth/access.lua
index ed124f5eaed..32e2729b320 100644
--- a/kong/plugins/basic-auth/access.lua
+++ b/kong/plugins/basic-auth/access.lua
@@ -158,7 +158,7 @@ function _M.execute(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                        nil, load_consumer_into_memory, conf.anonymous, true)
diff --git a/kong/plugins/hmac-auth/access.lua b/kong/plugins/hmac-auth/access.lua
index 10b6fc14ea0..34617022931 100644
--- a/kong/plugins/hmac-auth/access.lua
+++ b/kong/plugins/hmac-auth/access.lua
@@ -210,7 +210,7 @@ function _M.execute(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                        nil, load_consumer_into_memory, conf.anonymous, true)
diff --git a/kong/plugins/jwt/handler.lua b/kong/plugins/jwt/handler.lua
index a4be97ecac6..e0cc77f0572 100644
--- a/kong/plugins/jwt/handler.lua
+++ b/kong/plugins/jwt/handler.lua
@@ -180,7 +180,7 @@ function JwtHandler:access(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                        nil, load_consumer, conf.anonymous, true)
diff --git a/kong/plugins/key-auth/handler.lua b/kong/plugins/key-auth/handler.lua
index 79d0dcd6d1c..56391c6491d 100644
--- a/kong/plugins/key-auth/handler.lua
+++ b/kong/plugins/key-auth/handler.lua
@@ -157,7 +157,7 @@ function KeyAuthHandler:access(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                             nil, load_consumer, conf.anonymous, true)
diff --git a/kong/plugins/ldap-auth/access.lua b/kong/plugins/ldap-auth/access.lua
index 5956c581483..48d46a86baf 100644
--- a/kong/plugins/ldap-auth/access.lua
+++ b/kong/plugins/ldap-auth/access.lua
@@ -167,7 +167,7 @@ function _M.execute(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                        nil, load_consumer, conf.anonymous, true)
diff --git a/kong/plugins/oauth2/access.lua b/kong/plugins/oauth2/access.lua
index 746fd56e26b..ccfcfee9bb1 100644
--- a/kong/plugins/oauth2/access.lua
+++ b/kong/plugins/oauth2/access.lua
@@ -560,7 +560,7 @@ function _M.execute(conf)
 
   local ok, err = do_authentication(conf)
   if not ok then
-    if conf.anonymous ~= "" then
+    if conf.anonymous ~= "" and conf.anonymous ~= nil then
       -- get anonymous user
       local consumer, err = cache.get_or_set(cache.consumer_key(conf.anonymous),
                        nil, load_consumer_into_memory, conf.anonymous, true)