diff --git a/ChangeLog b/ChangeLog
index 249714c68e..d0e5262078 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Feb  6 20:44:24 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in: check __int64_t and __int128_t for RUBY_DEFINT on
+	  OS X.
+
 Sat Feb  6 15:18:28 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>
 
 	* test/ruby/enc/test_regex_casefold.rb: Added data-based testing for
diff --git a/configure.in b/configure.in
index 040484b5ab..30e40b9a78 100644
--- a/configure.in
+++ b/configure.in
@@ -1473,6 +1473,8 @@ RUBY_CHECK_SIZEOF(long, [int], [ILP LP])
 RUBY_CHECK_SIZEOF(long long)
 RUBY_CHECK_SIZEOF(__int64)
 RUBY_CHECK_SIZEOF(__int128)
+RUBY_CHECK_SIZEOF(__int64_t)
+RUBY_CHECK_SIZEOF(__int128_t)
 RUBY_CHECK_SIZEOF(off_t)
 RUBY_CHECK_SIZEOF(void*, [int long "long long"], [ILP LP LLP])
 RUBY_CHECK_SIZEOF(float)
@@ -2007,6 +2009,8 @@ typedef $1 t; int s = sizeof(t) == 42;])],
     ["$ac_cv_sizeof_int"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])int"],
     ["$ac_cv_sizeof_long"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])long"],
     ["$ac_cv_sizeof_long_long"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])long long"],
+    ["$ac_cv_sizeof___int64_t"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])__int64_t"],
+    ["$ac_cv_sizeof___int128_t"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])__int128_t"],
     ["$ac_cv_sizeof___int64"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])__int64"],
     ["$ac_cv_sizeof___int128"], [ rb_cv_type_$1="m4_if([$3], [], [], [$3 ])__int128"],
     [ rb_cv_type_$1=no])])])