diff --git a/rjit_c.rb b/rjit_c.rb
index 60c3635381..fe6cd38678 100644
--- a/rjit_c.rb
+++ b/rjit_c.rb
@@ -307,10 +307,6 @@ module RubyVM::RJIT # :nodoc: all
       }
     end
 
-    def obj_is_kind_of(obj, c)
-      Primitive.cexpr! 'rb_obj_is_kind_of(obj, c)'
-    end
-
     def rb_obj_class(obj)
       Primitive.cexpr! 'rb_obj_class(obj)'
     end