diff --git a/ChangeLog b/ChangeLog
index 12c80f13ae..716bd41dc7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Jul  1 12:02:39 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (rb_cstr_to_inum): Skip leading zeros.
+
 Mon Jul  1 00:59:23 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (nlz16): New function.
diff --git a/bignum.c b/bignum.c
index 4c06a7ae59..9b3cf2745d 100644
--- a/bignum.c
+++ b/bignum.c
@@ -2028,6 +2028,9 @@ rb_cstr_to_inum(const char *str, int base, int badcheck)
 	}
     }
 
+    while (buf < p && *buf == 0)
+        buf++;
+
     if (POW2_P(base)) {
         int flags = INTEGER_PACK_BIG_ENDIAN;
         if (!sign)