diff --git a/src/portmanager.cpp b/src/portmanager.cpp
index 4b37e6c..4ab63c1 100644
--- a/src/portmanager.cpp
+++ b/src/portmanager.cpp
@@ -42,11 +42,13 @@ void PortManager::Refresh()
 
 	const char **ports = jack_get_ports(client, NULL, NULL, 0);
 
-	for (int i = 0; ports[i] != NULL; ++i) {
-		Add(jack_port_by_name(client, ports[i]));
-	}
+	if (ports != NULL) {
+		for (int i = 0; ports[i] != NULL; ++i) {
+			Add(jack_port_by_name(client, ports[i]));
+		}
 
-	jack_free(ports);
+		jack_free(ports);
+	}
 
 	RefreshConnections();
 }