diff --git a/candm.h b/candm.h
index 7c36779..acc6cdf 100644
--- a/candm.h
+++ b/candm.h
@@ -292,7 +292,8 @@ typedef struct {
   Float offset;
   uint32_t flags;
   int32_t filter_length;
-  uint32_t reserved[3];
+  uint32_t cert_set;
+  uint32_t reserved[2];
   int32_t EOR;
 } REQ_NTP_Source;
 
diff --git a/client.c b/client.c
index f12511b..45239c6 100644
--- a/client.c
+++ b/client.c
@@ -1100,6 +1100,7 @@ process_cmd_add_source(CMD_Request *msg, char *line)
           (data.params.sel_options & SRC_SELECT_TRUST ? REQ_ADDSRC_TRUST : 0) |
           (data.params.sel_options & SRC_SELECT_REQUIRE ? REQ_ADDSRC_REQUIRE : 0));
       msg->data.ntp_source.filter_length = htonl(data.params.filter_length);
+      msg->data.ntp_source.cert_set = htonl(data.params.cert_set);
       memset(msg->data.ntp_source.reserved, 0, sizeof (msg->data.ntp_source.reserved));
 
       result = 1;
diff --git a/cmdmon.c b/cmdmon.c
index 6222f60..afdfa6c 100644
--- a/cmdmon.c
+++ b/cmdmon.c
@@ -735,7 +735,7 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
   params.filter_length = ntohl(rx_message->data.ntp_source.filter_length);
   params.authkey = ntohl(rx_message->data.ntp_source.authkey);
   params.nts_port = ntohl(rx_message->data.ntp_source.nts_port);
-  params.cert_set = 0;
+  params.cert_set = ntohl(rx_message->data.ntp_source.cert_set);
   params.max_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay);
   params.max_delay_ratio =
     UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_ratio);
diff --git a/test/simulation/110-chronyc b/test/simulation/110-chronyc
index d578bf2..c517249 100755
--- a/test/simulation/110-chronyc
+++ b/test/simulation/110-chronyc
@@ -101,7 +101,7 @@ limit=1
 for chronyc_conf in \
 	"accheck 1.2.3.4" \
 	"add peer 10.0.0.0 minpoll 2 maxpoll 6" \
-	"add server 10.0.0.0 minpoll 6 maxpoll 10 iburst burst key 1 maxdelay 1e-3 maxdelayratio 10.0 maxdelaydevratio 10.0 mindelay 1e-4 asymmetry 0.5 offset 1e-5 minsamples 6 maxsamples 6 filter 3 offline auto_offline prefer noselect trust require xleave polltarget 20 port 123 presend 7 minstratum 3 version 4" \
+	"add server 10.0.0.0 minpoll 6 maxpoll 10 iburst burst key 1 certset 2 maxdelay 1e-3 maxdelayratio 10.0 maxdelaydevratio 10.0 mindelay 1e-4 asymmetry 0.5 offset 1e-5 minsamples 6 maxsamples 6 filter 3 offline auto_offline prefer noselect trust require xleave polltarget 20 port 123 presend 7 minstratum 3 version 4" \
 	"add server node1.net1.clk" \
 	"allow 1.2.3.4" \
 	"allow 1.2" \