diff --git a/libraries/libldap/controls.c b/libraries/libldap/controls.c
index 12f455be98..f3af141e1e 100644
--- a/libraries/libldap/controls.c
+++ b/libraries/libldap/controls.c
@@ -285,7 +285,7 @@ ldap_controls_dup( LDAPControl *const *controls )
 		return NULL;
 	}
 
-	new = (LDAPControl **) LDAP_MALLOC( i * sizeof(LDAPControl *) );
+	new = (LDAPControl **) LDAP_MALLOC( (i+1) * sizeof(LDAPControl *) );
 
 	if( new == NULL ) {
 		/* memory allocation failure */