diff --git a/THANKS b/THANKS
index 36dd33a..ac50d08 100644
--- a/THANKS
+++ b/THANKS
@@ -6,4 +6,7 @@ David Lichteblau found lots of problems in the ASN.1 code.
 
 Thomas Walpuski has found lots of problems with the LDAP code.
 
-Dirk Meyer helped BSD portability
+Dirk Meyer helped BSD portability.
+
+Zak Johnson fixed substring matches in ldap_match_mapped.
+
diff --git a/ldap_match_mapped.c b/ldap_match_mapped.c
index a8a5078..7e627c8 100644
--- a/ldap_match_mapped.c
+++ b/ldap_match_mapped.c
@@ -31,8 +31,8 @@ found:
     case any:
       {
 	unsigned long len=str_len(attr);
-	if (len>x->s.l) return 0;
-	for (i=0; i<x->s.l-len; ++i)
+	if (len<x->s.l) return 0;
+	for (i=0; i<=len-x->s.l; ++i)
 	  if (!diff(x->s.s,x->s.l,attr+i))
 	    goto found;
       }