diff --git a/lib/fluent/oj_options.rb b/lib/fluent/oj_options.rb
index f1c274c119..a76e1f81ba 100644
--- a/lib/fluent/oj_options.rb
+++ b/lib/fluent/oj_options.rb
@@ -11,7 +11,7 @@ class OjOptions
 
     ALLOWED_VALUES = {
       'bigdecimal_load': %i[bigdecimal float auto],
-      'mode': %i[strict null compat json rails object custom]
+      'mode': %i[strict null compat json rails custom]
     }
 
     DEFAULTS = {