diff --git a/mrbgems/mruby-proc-ext/test/proc.c b/mrbgems/mruby-proc-ext/test/proc.c
index 0253f2b60..1de8debe7 100644
--- a/mrbgems/mruby-proc-ext/test/proc.c
+++ b/mrbgems/mruby-proc-ext/test/proc.c
@@ -56,7 +56,7 @@ void mrb_mruby_proc_ext_gem_test(mrb_state *mrb)
   struct RClass *cls;
 
   cls = mrb_define_class(mrb, "ProcExtTest", mrb->object_class);
-  mrb_define_module_function(mrb, cls, "mrb_proc_new_cfunc_with_env", proc_new_cfunc_with_env, MRB_ARGS_REQ(1));
-  mrb_define_module_function(mrb, cls, "mrb_cfunc_env_get", cfunc_env_get, MRB_ARGS_REQ(2));
-  mrb_define_module_function(mrb, cls, "cfunc_without_env", cfunc_without_env, MRB_ARGS_NONE());
+  mrb_define_class_method(mrb, cls, "mrb_proc_new_cfunc_with_env", proc_new_cfunc_with_env, MRB_ARGS_REQ(1));
+  mrb_define_class_method(mrb, cls, "mrb_cfunc_env_get", cfunc_env_get, MRB_ARGS_REQ(2));
+  mrb_define_method(mrb, cls, "cfunc_without_env", cfunc_without_env, MRB_ARGS_NONE());
 }