diff --git a/mrbgems/mruby-sleep/src/sleep.c b/mrbgems/mruby-sleep/src/sleep.c
index 6e98d80a2..7e8556a1e 100644
--- a/mrbgems/mruby-sleep/src/sleep.c
+++ b/mrbgems/mruby-sleep/src/sleep.c
@@ -172,8 +172,8 @@ f_usleep(mrb_state *mrb, mrb_value self)
 void
 mrb_mruby_sleep_gem_init(mrb_state *mrb)
 {
-  mrb_define_private_method_id(mrb, mrb->kernel_module, MRB_SYM(sleep),   f_sleep,   MRB_ARGS_REQ(1));
-  mrb_define_private_method_id(mrb, mrb->kernel_module, MRB_SYM(usleep),  f_usleep,  MRB_ARGS_REQ(1));
+  mrb_define_module_function_id(mrb, mrb->kernel_module, MRB_SYM(sleep),   f_sleep,   MRB_ARGS_REQ(1));
+  mrb_define_module_function_id(mrb, mrb->kernel_module, MRB_SYM(usleep),  f_usleep,  MRB_ARGS_REQ(1));
 }
 
 /*
diff --git a/mrbgems/mruby-task/src/task.c b/mrbgems/mruby-task/src/task.c
index 5fbfc2cf0..be23274e0 100644
--- a/mrbgems/mruby-task/src/task.c
+++ b/mrbgems/mruby-task/src/task.c
@@ -1103,13 +1103,13 @@ mrb_mruby_task_gem_init(mrb_state *mrb)
   mrb_define_method_id(mrb, task_class, MRB_SYM(terminate),   mrb_task_terminate,    MRB_ARGS_NONE());
   mrb_define_method_id(mrb, task_class, MRB_SYM(join),        mrb_task_join,         MRB_ARGS_NONE());
 
-  /* Kernel methods
+  /* Kernel methods (module functions like CRuby)
    * Note: sleep and usleep override mruby-sleep's implementation to be task-aware
    * (cooperative sleep within tasks, blocking sleep otherwise)
    */
-  mrb_define_private_method_id(mrb, mrb->kernel_module, MRB_SYM(sleep),    mrb_f_sleep,    MRB_ARGS_OPT(1));
-  mrb_define_private_method_id(mrb, mrb->kernel_module, MRB_SYM(usleep),   mrb_f_usleep,   MRB_ARGS_REQ(1));
-  mrb_define_private_method_id(mrb, mrb->kernel_module, MRB_SYM(sleep_ms), mrb_f_sleep_ms, MRB_ARGS_REQ(1));
+  mrb_define_module_function_id(mrb, mrb->kernel_module, MRB_SYM(sleep),    mrb_f_sleep,    MRB_ARGS_OPT(1));
+  mrb_define_module_function_id(mrb, mrb->kernel_module, MRB_SYM(usleep),   mrb_f_usleep,   MRB_ARGS_REQ(1));
+  mrb_define_module_function_id(mrb, mrb->kernel_module, MRB_SYM(sleep_ms), mrb_f_sleep_ms, MRB_ARGS_REQ(1));
 }
 
 void