diff --git a/libsofia-sip-ua/msg/msg_mime.c b/libsofia-sip-ua/msg/msg_mime.c
index 430d3f68f..a8bc48660 100644
--- a/libsofia-sip-ua/msg/msg_mime.c
+++ b/libsofia-sip-ua/msg/msg_mime.c
@@ -401,7 +401,7 @@ msg_multipart_t *msg_multipart_parse(su_home_t *home,
   m = strlen(boundary) - 2, blen = m - 1;
 
   /* Find first delimiter */
-  if (memcmp(boundary + 2, p, m - 2) == 0)
+  if (len >= m - 2 && memcmp(boundary + 2, p, m - 2) == 0)
     b = p, p = p + m - 2;
   else if ((p = memmem(p, len, boundary + 1, m - 1))) {
     if (p != pl->pl_data && p[-1] == '\r')