diff --git a/ChangeLog b/ChangeLog
index 2c027ef85d..a380f731bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Mon Jul 15 14:40:00 2013  Tanaka Akira  <akr@fsij.org>
+
+	* include/ruby/intern.h (rb_big2str0): Deprecated.
+
+	* bignum.c (rb_big2str1): Renamed from rb_big2str0.
+	  (rb_big2str0): Deprecated wrapper for rb_big2str1.
+	  (rb_big2str): Invoke rb_big2str1 instead of rb_big2str0.
+
 Mon Jul 15 14:13:02 2013  Masaki Matsushita  <glass.saga@gmail.com>
 
 	* struct.c (rb_struct_each_pair): use rb_yield_values(2, key, value)
diff --git a/bignum.c b/bignum.c
index 7c75bcf904..2a4f25e987 100644
--- a/bignum.c
+++ b/bignum.c
@@ -3540,8 +3540,8 @@ big2str_base_powerof2(VALUE x, size_t len, int base, int trim)
     return result;
 }
 
-VALUE
-rb_big2str0(VALUE x, int base, int trim)
+static VALUE
+rb_big2str1(VALUE x, int base, int trim)
 {
     int off;
     VALUE ss, xx;
@@ -3591,10 +3591,17 @@ rb_big2str0(VALUE x, int base, int trim)
     return ss;
 }
 
+/* deprecated */
+VALUE
+rb_big2str0(VALUE x, int base, int trim)
+{
+    return rb_big2str1(x, base, trim);
+}
+
 VALUE
 rb_big2str(VALUE x, int base)
 {
-    return rb_big2str0(x, base, 1);
+    return rb_big2str1(x, base, 1);
 }
 
 /*
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index df9d4af8d0..21adcca752 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -101,7 +101,7 @@ VALUE rb_str_to_inum(VALUE, int, int);
 VALUE rb_cstr2inum(const char*, int);
 VALUE rb_str2inum(VALUE, int);
 VALUE rb_big2str(VALUE, int);
-VALUE rb_big2str0(VALUE, int, int);
+DEPRECATED(VALUE rb_big2str0(VALUE, int, int));
 SIGNED_VALUE rb_big2long(VALUE);
 #define rb_big2int(x) rb_big2long(x)
 VALUE rb_big2ulong(VALUE);