diff --git a/lib/src/clixon_netconf_lib.c b/lib/src/clixon_netconf_lib.c
index 9a7d0194..97d81b1d 100644
--- a/lib/src/clixon_netconf_lib.c
+++ b/lib/src/clixon_netconf_lib.c
@@ -1725,7 +1725,7 @@ netconf_hello_server(clicon_handle h,
     cprintf(cb, "<capability>urn:ietf:params:netconf:capability:xpath:1.0</capability>");
     cprintf(cb, "<capability>urn:ietf:params:netconf:capability:notification:1.0</capability>");
     /* rfc6243 with-defaults capability modes */
-    cprintf(cb, "<capability>urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=explicit</capability>");
+    cprintf(cb, "<capability>urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=report-all&also-supported=explicit,trim</capability>");
     cprintf(cb, "</capabilities>");
     if (session_id) 
 	cprintf(cb, "<session-id>%lu</session-id>", (long unsigned int)session_id);
diff --git a/test/test_yang_with_defaults.sh b/test/test_yang_with_defaults.sh
index c6633ff8..bef0921b 100755
--- a/test/test_yang_with_defaults.sh
+++ b/test/test_yang_with_defaults.sh
@@ -172,7 +172,7 @@ wait_restconf
 
 new "rfc4243 4.3.  Capability Identifier"
 expecteof "$clixon_netconf -ef $cfg" 0 "$DEFAULTHELLO" \
-"<capability>urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=explicit</capability>"
+"<capability>urn:ietf:params:netconf:capability:with-defaults:1.0?basic-mode=report-all&also-supported=explicit,trim</capability>"
 
 new "rfc6243 3.1.  'report-all' Retrieval Mode"
 expecteof_netconf "$clixon_netconf -qf $cfg" 0 "$DEFAULTHELLO" \
@@ -377,6 +377,20 @@ expectpart "$(curl $CURLOPTS -X GET -H 'Accept: application/yang-data+xml' $RCPR
 "Cache-Control: no-cache" \
 '<interface xmlns="http://example.com/ns/interfaces"><name>eth1</name><status>ok</status></interface>'
 
+new "rfc8040 B.3.9. RESTONF with-defaults parameter = trim"
+expectpart "$(curl $CURLOPTS -X GET -H 'Accept: application/yang-data+json' $RCPROTO://localhost/restconf/data/example:interfaces/interface=eth1?with-defaults=trim)" \
+0 \
+"HTTP/$HVER 200" \
+"Content-Type: application/yang-data+json" \
+"Cache-Control: no-cache" \
+'{"example:interface":\[{"name":"eth1"}\]}'
+expectpart "$(curl $CURLOPTS -X GET -H 'Accept: application/yang-data+xml' $RCPROTO://localhost/restconf/data/example:interfaces/interface=eth1?with-defaults=trim)" \
+0 \
+"HTTP/$HVER 200" \
+"Content-Type: application/yang-data+xml" \
+"Cache-Control: no-cache" \
+'<interface xmlns="http://example.com/ns/interfaces"><name>eth1</name></interface>'
+
 
 if [ $RC -ne 0 ]; then
     new "Kill restconf daemon"