diff --git a/drivers/staging/greybus/connection.c b/drivers/staging/greybus/connection.c
index 4663397cb7e3..cac04dd71130 100644
--- a/drivers/staging/greybus/connection.c
+++ b/drivers/staging/greybus/connection.c
@@ -80,7 +80,10 @@ protocol_id_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
 	struct gb_connection *connection = to_gb_connection(dev);
 
-	return sprintf(buf, "%d\n", connection->protocol->id);
+	if (connection->protocol)
+		return sprintf(buf, "%d\n", connection->protocol->id);
+	else
+		return -EINVAL;
 }
 static DEVICE_ATTR_RO(protocol_id);