diff --git a/mrbgems/mruby-numeric-ext/src/numeric_ext.c b/mrbgems/mruby-numeric-ext/src/numeric_ext.c
index a29f0a4bd..6321a81eb 100644
--- a/mrbgems/mruby-numeric-ext/src/numeric_ext.c
+++ b/mrbgems/mruby-numeric-ext/src/numeric_ext.c
@@ -2,6 +2,7 @@
 #include <mruby/numeric.h>
 #include <mruby/array.h>
 #include <mruby/string.h>
+#include <mruby/class.h>
 #include <mruby/internal.h>
 #include <mruby/presym.h>
 
@@ -479,14 +480,51 @@ int_sqrt(mrb_state *mrb, mrb_value self)
   }
 }
 
+#ifndef MRB_NO_PRESYM
+#define INTEGER_EXT_ROM_MT_SIZE 9
+static struct {
+  union mt_ptr vals[INTEGER_EXT_ROM_MT_SIZE];
+  mrb_sym keys[INTEGER_EXT_ROM_MT_SIZE];
+} integer_ext_rom_data = {
+  .vals = {
+    { .func = int_remainder },
+    { .func = int_powm },
+    { .func = int_digits },
+    { .func = int_size },
+    { .func = int_bit_length },
+    { .func = int_odd },
+    { .func = int_even },
+    { .func = int_gcd },
+    { .func = int_lcm },
+  },
+  .keys = {
+    MT_KEY(MRB_SYM(remainder),  MT_FUNC|MT_PUBLIC),
+    MT_KEY(MRB_SYM(pow),        MT_FUNC|MT_PUBLIC),
+    MT_KEY(MRB_SYM(digits),     MT_FUNC|MT_PUBLIC),
+    MT_KEY(MRB_SYM(size),       MT_FUNC|MT_NOARG|MT_PUBLIC),
+    MT_KEY(MRB_SYM(bit_length), MT_FUNC|MT_NOARG|MT_PUBLIC),
+    MT_KEY(MRB_SYM_Q(odd),      MT_FUNC|MT_NOARG|MT_PUBLIC),
+    MT_KEY(MRB_SYM_Q(even),     MT_FUNC|MT_NOARG|MT_PUBLIC),
+    MT_KEY(MRB_SYM(gcd),        MT_FUNC|MT_PUBLIC),
+    MT_KEY(MRB_SYM(lcm),        MT_FUNC|MT_PUBLIC),
+  }
+};
+static mt_tbl integer_ext_rom_mt = {
+  INTEGER_EXT_ROM_MT_SIZE, INTEGER_EXT_ROM_MT_SIZE,
+  (union mt_ptr*)&integer_ext_rom_data, NULL
+};
+#endif /* !MRB_NO_PRESYM */
+
 void
 mrb_mruby_numeric_ext_gem_init(mrb_state* mrb)
 {
   struct RClass *ic = mrb->integer_class;
 
   mrb_define_alias_id(mrb, ic, MRB_SYM(modulo), MRB_OPSYM(mod));
+#ifndef MRB_NO_PRESYM
+  mrb_mt_init_rom(ic, &integer_ext_rom_mt);
+#else
   mrb_define_method_id(mrb, ic, MRB_SYM(remainder), int_remainder, MRB_ARGS_REQ(1));
-
   mrb_define_method_id(mrb, ic, MRB_SYM(pow), int_powm, MRB_ARGS_ARG(1,1));
   mrb_define_method_id(mrb, ic, MRB_SYM(digits), int_digits, MRB_ARGS_OPT(1));
   mrb_define_method_id(mrb, ic, MRB_SYM(size), int_size, MRB_ARGS_NONE());
@@ -495,6 +533,7 @@ mrb_mruby_numeric_ext_gem_init(mrb_state* mrb)
   mrb_define_method_id(mrb, ic, MRB_SYM_Q(even), int_even, MRB_ARGS_NONE());
   mrb_define_method_id(mrb, ic, MRB_SYM(gcd), int_gcd, MRB_ARGS_REQ(1));
   mrb_define_method_id(mrb, ic, MRB_SYM(lcm), int_lcm, MRB_ARGS_REQ(1));
+#endif
   mrb_define_class_method_id(mrb, ic, MRB_SYM(sqrt), int_sqrt, MRB_ARGS_REQ(1));
 
 #ifndef MRB_NO_FLOAT