diff --git a/ChangeLog b/ChangeLog
index 17343394d3..290a58aac8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 19 23:19:35 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* regexec.c (slow_search): check the case when the length is 1.
+	  The behavior of memcmp is undefined if the third argument is 0.
+
 Mon May 19 21:07:48 2008  Koichi Sasada  <ko1@atdot.net>
 
 	* thread_pthread.c (native_thread_apply_priority): 
diff --git a/regexec.c b/regexec.c
index a2d6993d08..684c5c86d4 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2765,7 +2765,7 @@ slow_search(OnigEncoding enc, UChar* target, UChar* target_end,
       if (*s == *target) {
 	p = s + 1;
 	t = target + 1;
-	if (memcmp(t, p, target_end - t) == 0)
+	if (target_end == t || memcmp(t, p, target_end - t) == 0)
 	  return s;
       }
       s += n;
@@ -2776,7 +2776,7 @@ slow_search(OnigEncoding enc, UChar* target, UChar* target_end,
     if (*s == *target) {
       p = s + 1;
       t = target + 1;
-      if (memcmp(t, p, target_end - t) == 0)
+      if (target_end == t || memcmp(t, p, target_end - t) == 0)
 	return s;
     }
     s += enclen(enc, s, end);