diff --git a/test/unit/persist_read_stubs.c b/test/unit/persist_read_stubs.c
index 62b03567..b0b30d7b 100644
--- a/test/unit/persist_read_stubs.c
+++ b/test/unit/persist_read_stubs.c
@@ -186,3 +186,9 @@ void db__msg_store_ref_inc(struct mosquitto_msg_store *store)
 	store->ref_count++;
 }
 
+void callback__on_disconnect(struct mosquitto *mosq, int rc, const mosquitto_property *props)
+{
+	UNUSED(mosq);
+	UNUSED(rc);
+	UNUSED(props);
+}
diff --git a/test/unit/persist_write_stubs.c b/test/unit/persist_write_stubs.c
index 173cd4ea..b2cae03c 100644
--- a/test/unit/persist_write_stubs.c
+++ b/test/unit/persist_write_stubs.c
@@ -113,3 +113,10 @@ int send__pubrel(struct mosquitto *mosq, uint16_t mid, const mosquitto_property
 
 	return MOSQ_ERR_SUCCESS;
 }
+
+void callback__on_disconnect(struct mosquitto *mosq, int rc, const mosquitto_property *props)
+{
+	UNUSED(mosq);
+	UNUSED(rc);
+	UNUSED(props);
+}
diff --git a/test/unit/stubs.c b/test/unit/stubs.c
index 23fa36fd..432c118e 100644
--- a/test/unit/stubs.c
+++ b/test/unit/stubs.c
@@ -36,3 +36,9 @@ int send__pingreq(struct mosquitto *mosq)
 	return MOSQ_ERR_SUCCESS;
 }
 
+void callback__on_disconnect(struct mosquitto *mosq, int rc, const mosquitto_property *props)
+{
+	UNUSED(mosq);
+	UNUSED(rc);
+	UNUSED(props);
+}