diff -up net-snmp-5.7.2/snmplib/snmp_api.c.original net-snmp-5.7.2/snmplib/snmp_api.c
--- net-snmp-5.7.2/snmplib/snmp_api.c.original	2018-01-12 17:46:47.534166712 +0900
+++ net-snmp-5.7.2/snmplib/snmp_api.c	2018-01-12 17:48:09.420911255 +0900
@@ -4974,6 +4974,9 @@ _sess_async_send(void *sessp,
 
     reqid = pdu->reqid;
 
+    if (0 == reqid && (SNMPERR_SUCCESS == session->s_snmp_errno))
+        ++reqid;
+
     /*
      * Add to pending requests list if we expect a response.  
      */
diff -up net-snmp-5.7.2/snmplib/snmp_client.c.original net-snmp-5.7.2/snmplib/snmp_client.c
--- net-snmp-5.7.2/snmplib/snmp_client.c.original	2018-01-12 17:48:21.814721234 +0900
+++ net-snmp-5.7.2/snmplib/snmp_client.c	2018-01-12 18:33:55.779642445 +0900
@@ -1044,11 +1044,13 @@ snmp_synch_response_cb(netsnmp_session *
     ss->callback = pcb;
     ss->callback_magic = (void *) state;
 
-    if ((state->reqid = snmp_send(ss, pdu)) == 0) {
+    if (snmp_send(ss, pdu) == 0) {
         snmp_free_pdu(pdu);
         state->status = STAT_ERROR;
-    } else
+    } else {
+        state->reqid = pdu->reqid;
         state->waiting = 1;
+    }
 
     while (state->waiting) {
         numfds = 0;
@@ -1136,11 +1138,13 @@ snmp_sess_synch_response(void *sessp,
     ss->callback = snmp_synch_input;
     ss->callback_magic = (void *) state;
 
-    if ((state->reqid = snmp_sess_send(sessp, pdu)) == 0) {
+    if (snmp_sess_send(sessp, pdu) == 0) {
         snmp_free_pdu(pdu);
         state->status = STAT_ERROR;
-    } else
+    } else {
+	state->reqid = pdu->reqid;
         state->waiting = 1;
+    }
 
     while (state->waiting) {
         numfds = 0;