diff --git a/src/io.c b/src/io.c
index 4453f2d6d..fc343984a 100644
--- a/src/io.c
+++ b/src/io.c
@@ -730,7 +730,7 @@ mrb_init_io(mrb_state *mrb)
   io      = mrb_define_class(mrb, "IO", mrb->object_class);
   MRB_SET_INSTANCE_TT(io, MRB_TT_DATA);
 
-  mrb_include_module(mrb, io, mrb_class_get(mrb, "Enumerable")); /* 15.2.20.3 */
+  mrb_include_module(mrb, io, mrb_module_get(mrb, "Enumerable")); /* 15.2.20.3 */
 
   mrb_define_class_method(mrb, io, "_popen",  mrb_io_s_popen,   MRB_ARGS_ANY());
   mrb_define_class_method(mrb, io, "for_fd",  mrb_io_s_for_fd,  MRB_ARGS_REQ(1)|MRB_ARGS_OPT(2));