diff --git a/ChangeLog b/ChangeLog
index 6436a9127..f6a001a9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,10 @@
+Wed May  2 10:30:39 CEST 2007 (tk)
+----------------------------------
+  * libclamav/matcher-ac.c: fix boundary error (bb#491)
+
 Tue May  1 22:26:00 EEST 2007 (edwin)
 ----------------------------------
-  libclamav/htmlnorm.c: fix uninitialized value warning
+  * libclamav/htmlnorm.c: fix uninitialized value warning
 
 Tue May  1 18:13:09 BST 2007 (njh)
 ----------------------------------
diff --git a/libclamav/matcher-ac.c b/libclamav/matcher-ac.c
index 91dcb0ec1..86e256369 100644
--- a/libclamav/matcher-ac.c
+++ b/libclamav/matcher-ac.c
@@ -334,6 +334,9 @@ inline static int ac_findmatch(const unsigned char *buffer, uint32_t offset, uin
 	uint8_t found;
 
 
+    if(offset + pattern->length > length)
+	return 0;
+
     if(pattern->prefix)
 	if(pattern->prefix_length > offset)
 	    return 0;