diff --git a/src/Authorizer.cpp b/src/Authorizer.cpp
index f2caa32..1718384 100644
--- a/src/Authorizer.cpp
+++ b/src/Authorizer.cpp
@@ -46,7 +46,7 @@ void Authorizer::add_unknown(const std::string& username)
 
 bool Authorizer::is_unknown(const std::string& username)
 {
-    return _unknownList.confirm(username);
+    return (username.empty() or _unknownList.confirm(username));
 }
 
 bool Authorizer::add(const std::string& token, const std::string& username)
diff --git a/src/jwp-plugin.cpp b/src/jwp-plugin.cpp
index fa432f9..90c2e89 100644
--- a/src/jwp-plugin.cpp
+++ b/src/jwp-plugin.cpp
@@ -102,7 +102,13 @@ int jwp_auth_basic_auth_callback(int event, void *event_data, void *userdata)
 
     struct mosquitto_evt_basic_auth *auth_data = static_cast<struct mosquitto_evt_basic_auth*>(event_data);
 
-    if(!auth_data->username or !auth_data->password)
+    if(!auth_data->username)
+    {
+        // We need a username to do anything.
+        return MOSQ_ERR_PLUGIN_DEFER;
+    }
+
+    if(!auth_data->password)
     {
         authorizer->add_unknown(std::string(auth_data->username));
         return MOSQ_ERR_PLUGIN_DEFER;
diff --git a/test/run.sh b/test/run.sh
index 41323fa..872a188 100755
--- a/test/run.sh
+++ b/test/run.sh
@@ -1,2 +1,2 @@
 #!/usr/bin/env bash
-/usr/local/sbin/mosquitto -v -c $PWD/mosquitto.conf
+/usr/sbin/mosquitto -v -c $PWD/mosquitto.conf