diff --git a/src/transport_layer/stun_nat.c b/src/transport_layer/stun_nat.c
index 80c23aa2..f644b2ad 100644
--- a/src/transport_layer/stun_nat.c
+++ b/src/transport_layer/stun_nat.c
@@ -656,7 +656,7 @@ static void restart_probe(struct stun_probe* p) {
 static void scan_sources(struct STUN_NAT* mod) {
     for (struct stun_probe* p = mod->probes; p; p = p->next) p->seen = 0;
     for (struct ETCP_SOCKET* sock = mod->inst->etcp_sockets; sock; sock = sock->next) {
-        if (sock->is_tcp) continue;
+        if (sock->is_tcp || sock->probe_only) continue;
         struct stun_source source;
         if (source_snapshot(sock, &source) < 0) continue;
         struct stun_probe** slot = &mod->probes;
diff --git a/tests/test_stun_nat.c b/tests/test_stun_nat.c
index 6a8d0b45..506faa17 100644
--- a/tests/test_stun_nat.c
+++ b/tests/test_stun_nat.c
@@ -157,7 +157,10 @@ static void fixture_init(struct fixture* f) {
     assert(!getsockname(f->source.fd, (struct sockaddr*)&f->source.local_addr, &size));
     f->source.interface_addr = f->source.local_addr;
     f->source.instance = &f->inst;
-    f->source.nat_type = NAT_VERIFIED_STRICT;
+    f->source.address_profile.mapping = ADDRESS_MAP_DEPENDENT;
+    f->source.address_profile.inbound = ADDRESS_IN_CONTACT;
+    f->source.address_profile.evidence_id = 1;
+    f->source.address_profile.checked_at = 1;
     f->source.nat_addr = f->source.local_addr;
     snprintf(f->source.name, sizeof(f->source.name), "source");
     f->inst.etcp_sockets = &f->source;
@@ -307,6 +310,19 @@ int main(void) {
     run_case("unstable mapping", &unstable, STUN_MAP_UNKNOWN, STUN_FILTER_UNKNOWN);
     struct fixture direct = { .rfc = 1, .direct = 1, .mapping = STUN_MAP_EIM, .filtering = STUN_FILTER_EIF };
     run_case("no translation", &direct, STUN_MAP_EIM, STUN_FILTER_EIF);
+    struct fixture helpers = { .mapping = STUN_MAP_EIM };
+    fixture_init(&helpers);
+    struct ETCP_SOCKET auxiliary = helpers.source;
+    auxiliary.probe_only = 1;
+    snprintf(auxiliary.name, sizeof(auxiliary.name), "nat-helper");
+    auxiliary.next = &helpers.source;
+    helpers.inst.etcp_sockets = &auxiliary;
+    fixture_start(&helpers, 0, 0, 0);
+    struct stun_nat_result helper_result = wait_result(&helpers);
+    assert(helper_result.mapping == STUN_MAP_MATCH);
+    assert(stun_nat_get_result(&helpers.inst, "nat-helper", &helper_result) < 0);
+    fixture_destroy(&helpers);
+    DEBUG_INFO(DEBUG_CATEGORY_NAT, "PASS STUN skips auxiliary NAT helper sockets");
     struct fixture duplicate = { .mapping = STUN_MAP_EIM };
     fixture_init(&duplicate);
     fixture_start(&duplicate, 0, 0, 1);