diff --git a/src/core/dnsmasq/nm-dnsmasq-utils.c b/src/core/dnsmasq/nm-dnsmasq-utils.c
index 86e18b5640..c2791b9e6c 100644
--- a/src/core/dnsmasq/nm-dnsmasq-utils.c
+++ b/src/core/dnsmasq/nm-dnsmasq-utils.c
@@ -5,9 +5,10 @@
 
 #include "src/core/nm-default-daemon.h"
 
+#include "nm-dnsmasq-utils.h"
+
 #include <arpa/inet.h>
 
-#include "nm-dnsmasq-utils.h"
 #include "libnm-platform/nm-platform.h"
 #include "nm-utils.h"
 
diff --git a/src/core/nm-dbus-object.c b/src/core/nm-dbus-object.c
index 6f294fe2ec..0414973929 100644
--- a/src/core/nm-dbus-object.c
+++ b/src/core/nm-dbus-object.c
@@ -183,23 +183,25 @@ nm_dbus_object_unexport_on_idle(gpointer /* (NMDBusObject *) */ self_take)
 
 /*****************************************************************************/
 
-void
+gboolean
 _nm_dbus_object_clear_and_unexport(NMDBusObject **location)
 {
     NMDBusObject *self;
 
-    g_return_if_fail(location);
+    g_return_val_if_fail(location, FALSE);
+
     if (!*location)
-        return;
+        return FALSE;
 
     self = g_steal_pointer(location);
 
-    g_return_if_fail(NM_IS_DBUS_OBJECT(self));
+    g_return_val_if_fail(NM_IS_DBUS_OBJECT(self), FALSE);
 
     if (self->internal.path)
         nm_dbus_object_unexport(self);
 
     g_object_unref(self);
+    return TRUE;
 }
 
 /*****************************************************************************/
diff --git a/src/core/nm-dbus-object.h b/src/core/nm-dbus-object.h
index d94bd5df45..c7c1b4f445 100644
--- a/src/core/nm-dbus-object.h
+++ b/src/core/nm-dbus-object.h
@@ -166,9 +166,9 @@ void        nm_dbus_object_unexport(gpointer /* (NMDBusObject *) */ self);
 
 void nm_dbus_object_unexport_on_idle(gpointer /* (NMDBusObject *) */ self_take);
 
-void _nm_dbus_object_clear_and_unexport(NMDBusObject **location);
+gboolean _nm_dbus_object_clear_and_unexport(NMDBusObject **location);
 #define nm_dbus_object_clear_and_unexport(location) \
-    _nm_dbus_object_clear_and_unexport((NMDBusObject **) (location))
+    _nm_dbus_object_clear_and_unexport(NM_CAST_PPTR(NMDBusObject, (location)))
 
 void nm_dbus_object_emit_signal_variant(NMDBusObject *                     self,
                                         const NMDBusInterfaceInfoExtended *interface_info,
diff --git a/src/core/nm-dhcp-config.c b/src/core/nm-dhcp-config.c
index c26b371dca..c77e0adbaf 100644
--- a/src/core/nm-dhcp-config.c
+++ b/src/core/nm-dhcp-config.c
@@ -59,6 +59,7 @@ struct _NMDhcpConfig {
 
 struct _NMDhcpConfigClass {
     NMDBusObjectClass parent;
+    int               addr_family;
 };
 
 G_DEFINE_ABSTRACT_TYPE(NMDhcpConfig, nm_dhcp_config, NM_TYPE_DBUS_OBJECT)
@@ -67,6 +68,14 @@ G_DEFINE_ABSTRACT_TYPE(NMDhcpConfig, nm_dhcp_config, NM_TYPE_DBUS_OBJECT)
 
 /*****************************************************************************/
 
+int
+nm_dhcp_config_get_addr_family(NMDhcpConfig *self)
+{
+    return NM_DHCP_CONFIG_GET_CLASS(self)->addr_family;
+}
+
+/*****************************************************************************/
+
 void
 nm_dhcp_config_set_options(NMDhcpConfig *self, GHashTable *options)
 {
@@ -197,10 +206,13 @@ static void
 nm_dhcp4_config_class_init(NMDhcp4ConfigClass *klass)
 {
     NMDBusObjectClass *dbus_object_class = NM_DBUS_OBJECT_CLASS(klass);
+    NMDhcpConfigClass *dhcp_config_class = NM_DHCP_CONFIG_CLASS(klass);
 
     dbus_object_class->export_path     = NM_DBUS_EXPORT_PATH_NUMBERED(NM_DBUS_PATH "/DHCP4Config");
     dbus_object_class->interface_infos = NM_DBUS_INTERFACE_INFOS(&interface_info_dhcp4_config);
     dbus_object_class->export_on_construction = TRUE;
+
+    dhcp_config_class->addr_family = AF_INET;
 }
 
 /*****************************************************************************/
@@ -234,8 +246,11 @@ static void
 nm_dhcp6_config_class_init(NMDhcp6ConfigClass *klass)
 {
     NMDBusObjectClass *dbus_object_class = NM_DBUS_OBJECT_CLASS(klass);
+    NMDhcpConfigClass *dhcp_config_class = NM_DHCP_CONFIG_CLASS(klass);
 
     dbus_object_class->export_path     = NM_DBUS_EXPORT_PATH_NUMBERED(NM_DBUS_PATH "/DHCP6Config");
     dbus_object_class->interface_infos = NM_DBUS_INTERFACE_INFOS(&interface_info_dhcp6_config);
     dbus_object_class->export_on_construction = TRUE;
+
+    dhcp_config_class->addr_family = AF_INET6;
 }
diff --git a/src/core/ppp/nm-ppp-manager.c b/src/core/ppp/nm-ppp-manager.c
index 137fccf31f..85f8d9aba6 100644
--- a/src/core/ppp/nm-ppp-manager.c
+++ b/src/core/ppp/nm-ppp-manager.c
@@ -1446,8 +1446,8 @@ nm_ppp_manager_class_init(NMPPPManagerClass *manager_class)
                                   NULL,
                                   G_TYPE_NONE,
                                   2,
-                                  G_TYPE_UINT /*guint32 in_bytes*/,
-                                  G_TYPE_UINT /*guint32 out_bytes*/);
+                                  G_TYPE_UINT,  /* guint32 in_bytes */
+                                  G_TYPE_UINT); /* guint32 out_bytes */
 }
 
 NMPPPOps ppp_ops = {
diff --git a/src/libnm-glib-aux/nm-macros-internal.h b/src/libnm-glib-aux/nm-macros-internal.h
index cc3b19c3a1..aaf5cff61a 100644
--- a/src/libnm-glib-aux/nm-macros-internal.h
+++ b/src/libnm-glib-aux/nm-macros-internal.h
@@ -683,6 +683,21 @@ NM_G_ERROR_MSG(GError *error)
     #define NM_STRUCT_OFFSET_ENSURE_TYPE(type, container, field) G_STRUCT_OFFSET(container, field)
 #endif
 
+/* Casts (arg) to (type**), but also having a compile time check that
+ * the arg is some sort of pointer to a pointer.
+ *
+ * The only purpose of this macro is some additional compile time safety,
+ * that the argument is a pointer to pointer. But then it will C cast any kind
+ * of such argument. */
+#define NM_CAST_PPTR(type, arg)                                   \
+    ({                                                            \
+        typeof(*(arg)) *const _arg         = (arg);               \
+        typeof(*_arg) _arg2                = _arg ? *_arg : NULL; \
+        _nm_unused const void *const _arg3 = _arg2;               \
+                                                                  \
+        (type **) _arg;                                           \
+    })
+
 #if _NM_CC_SUPPORT_GENERIC
     /* these macros cast (value) to
      *  - "const char **"      (for "MC", mutable-const)