diff --git a/src/modules/pv/pv_trans.c b/src/modules/pv/pv_trans.c
index 8ab46d328fa..9b512e860fd 100644
--- a/src/modules/pv/pv_trans.c
+++ b/src/modules/pv/pv_trans.c
@@ -837,6 +837,7 @@ int tr_eval_string(struct sip_msg *msg, tr_param_t *tp, int subtype,
 			if(!(val->flags&PV_VAL_STR))
 				val->rs.s = int2str(val->ri, &val->rs.len);
 
+
 			/* Set maximum prefix length */
 			max = val->rs.len;
 			if(tp!=NULL) {
@@ -875,7 +876,7 @@ int tr_eval_string(struct sip_msg *msg, tr_param_t *tp, int subtype,
 			memset(val, 0, sizeof(pv_value_t));
 			val->flags = PV_VAL_STR;
 			val->rs.s = _tr_buffer;
-			val->rs.len = j-1;
+			val->rs.len = (j>0)?(j-1):0;
 			break;