diff --git a/src/modules/pv/pv_trans.c b/src/modules/pv/pv_trans.c
index dfc842aac17..b95ffd135c5 100644
--- a/src/modules/pv/pv_trans.c
+++ b/src/modules/pv/pv_trans.c
@@ -838,6 +838,7 @@ 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) {
@@ -876,7 +877,7 @@ 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;