diff --git a/openbsc/tests/oap/oap_client_test.c b/openbsc/tests/oap/oap_client_test.c
index ab651e6..e6501cb 100644
--- a/openbsc/tests/oap/oap_client_test.c
+++ b/openbsc/tests/oap/oap_client_test.c
@@ -62,6 +62,10 @@
 	msgb_free(msg_rx);
 	OSMO_ASSERT(!msg_tx);
 
+	fprintf(stderr, "- NULL config should disable\n");
+	OSMO_ASSERT( oap_client_init(NULL, state) == 0 );
+	OSMO_ASSERT(state->state == OAP_DISABLED);
+
 	fprintf(stderr, "- reject messages in disabled state\n");
 	memset(state, 0, sizeof(*state));
 	memset(&oap_rx, 0, sizeof(oap_rx));
diff --git a/openbsc/tests/oap/oap_client_test.err b/openbsc/tests/oap/oap_client_test.err
index 8c538dc..62ddc9e 100644
--- a/openbsc/tests/oap/oap_client_test.err
+++ b/openbsc/tests/oap/oap_client_test.err
@@ -1,6 +1,7 @@
 - make sure filling with zeros means uninitialized
 - reject messages in uninitialized state
 DLOAP Received OAP message 5, but the OAP client is not initialized
+- NULL config should disable
 - reject messages in disabled state
 DLOAP Received OAP message 5, but the OAP client is disabled
 - invalid client_id and shared secret