diff --git a/libnm-glib/nm-dhcp4-config.c b/libnm-glib/nm-dhcp4-config.c
index fc3491c890..4acdeae76e 100644
--- a/libnm-glib/nm-dhcp4-config.c
+++ b/libnm-glib/nm-dhcp4-config.c
@@ -174,6 +174,9 @@ nm_dhcp4_config_class_init (NMDHCP4ConfigClass *config_class)
 GObject *
 nm_dhcp4_config_new (DBusGConnection *connection, const char *object_path)
 {
+	g_return_val_if_fail (connection != NULL, NULL);
+	g_return_val_if_fail (object_path != NULL, NULL);
+
 	return (GObject *) g_object_new (NM_TYPE_DHCP4_CONFIG,
 	                                 NM_OBJECT_DBUS_CONNECTION, connection,
 	                                 NM_OBJECT_DBUS_PATH, object_path,
diff --git a/libnm-glib/nm-dhcp6-config.c b/libnm-glib/nm-dhcp6-config.c
index 43aee15c7c..aebea8df6a 100644
--- a/libnm-glib/nm-dhcp6-config.c
+++ b/libnm-glib/nm-dhcp6-config.c
@@ -174,6 +174,9 @@ nm_dhcp6_config_class_init (NMDHCP6ConfigClass *config_class)
 GObject *
 nm_dhcp6_config_new (DBusGConnection *connection, const char *object_path)
 {
+	g_return_val_if_fail (connection != NULL, NULL);
+	g_return_val_if_fail (object_path != NULL, NULL);
+
 	return (GObject *) g_object_new (NM_TYPE_DHCP6_CONFIG,
 	                                 NM_OBJECT_DBUS_CONNECTION, connection,
 	                                 NM_OBJECT_DBUS_PATH, object_path,
diff --git a/libnm-glib/nm-ip4-config.c b/libnm-glib/nm-ip4-config.c
index ae7448f9fd..9e0e2e2d28 100644
--- a/libnm-glib/nm-ip4-config.c
+++ b/libnm-glib/nm-ip4-config.c
@@ -330,6 +330,9 @@ nm_ip4_config_class_init (NMIP4ConfigClass *config_class)
 GObject *
 nm_ip4_config_new (DBusGConnection *connection, const char *object_path)
 {
+	g_return_val_if_fail (connection != NULL, NULL);
+	g_return_val_if_fail (object_path != NULL, NULL);
+
 	return (GObject *) g_object_new (NM_TYPE_IP4_CONFIG,
 	                                 NM_OBJECT_DBUS_CONNECTION, connection,
 	                                 NM_OBJECT_DBUS_PATH, object_path,
diff --git a/libnm-glib/nm-ip6-config.c b/libnm-glib/nm-ip6-config.c
index 320f00f2d0..5ec02dae8b 100644
--- a/libnm-glib/nm-ip6-config.c
+++ b/libnm-glib/nm-ip6-config.c
@@ -69,6 +69,9 @@ enum {
 GObject *
 nm_ip6_config_new (DBusGConnection *connection, const char *object_path)
 {
+	g_return_val_if_fail (connection != NULL, NULL);
+	g_return_val_if_fail (object_path != NULL, NULL);
+
 	return (GObject *) g_object_new (NM_TYPE_IP6_CONFIG,
 	                                 NM_OBJECT_DBUS_CONNECTION, connection,
 	                                 NM_OBJECT_DBUS_PATH, object_path,