diff --git a/src/dhcp/nm-dhcp-client.c b/src/dhcp/nm-dhcp-client.c
index f1a62f2474..60901692fb 100644
--- a/src/dhcp/nm-dhcp-client.c
+++ b/src/dhcp/nm-dhcp-client.c
@@ -359,26 +359,25 @@ stop (NMDhcpClient *self, gboolean release, GBytes *duid)
 void
 nm_dhcp_client_set_state (NMDhcpClient *self,
                           NMDhcpState new_state,
-                          GObject *ip_config,
+                          NMIPConfig *ip_config,
                           GHashTable *options)
 {
 	NMDhcpClientPrivate *priv = NM_DHCP_CLIENT_GET_PRIVATE (self);
 	gs_free char *event_id = NULL;
 
+	if (new_state == NM_DHCP_STATE_BOUND) {
+		g_return_if_fail (NM_IS_IP_CONFIG (ip_config, priv->addr_family));
+		g_return_if_fail (options);
+	} else {
+		g_return_if_fail (!ip_config);
+		g_return_if_fail (!options);
+	}
+
 	if (new_state >= NM_DHCP_STATE_BOUND)
 		timeout_cleanup (self);
 	if (new_state >= NM_DHCP_STATE_TIMEOUT)
 		watch_cleanup (self);
 
-	if (new_state == NM_DHCP_STATE_BOUND) {
-		g_assert (   (priv->addr_family == AF_INET  && NM_IS_IP4_CONFIG (ip_config))
-		          || (priv->addr_family == AF_INET6 && NM_IS_IP6_CONFIG (ip_config)));
-		g_assert (options);
-	} else {
-		g_assert (ip_config == NULL);
-		g_assert (options == NULL);
-	}
-
 	/* The client may send same-state transitions for RENEW/REBIND events and
 	 * the lease may have changed, so handle same-state transitions for the
 	 * BOUND state.  Ignore same-state transitions for other events since
@@ -851,7 +850,7 @@ nm_dhcp_client_handle_event (gpointer unused,
 			g_clear_pointer (&str_options, g_hash_table_unref);
 		}
 
-		nm_dhcp_client_set_state (self, new_state, G_OBJECT (ip_config), str_options);
+		nm_dhcp_client_set_state (self, new_state, ip_config, str_options);
 	}
 
 	return TRUE;
diff --git a/src/dhcp/nm-dhcp-client.h b/src/dhcp/nm-dhcp-client.h
index f3c34d3dcf..111b063bd5 100644
--- a/src/dhcp/nm-dhcp-client.h
+++ b/src/dhcp/nm-dhcp-client.h
@@ -168,7 +168,7 @@ void nm_dhcp_client_watch_child (NMDhcpClient *self, pid_t pid);
 
 void nm_dhcp_client_set_state (NMDhcpClient *self,
                                NMDhcpState new_state,
-                               GObject *ip_config,   /* NMIP4Config or NMIP6Config */
+                               NMIPConfig *ip_config,
                                GHashTable *options); /* str:str hash */
 
 gboolean nm_dhcp_client_handle_event (gpointer unused,
diff --git a/src/dhcp/nm-dhcp-systemd.c b/src/dhcp/nm-dhcp-systemd.c
index 8cd80abe82..2d0202bb70 100644
--- a/src/dhcp/nm-dhcp-systemd.c
+++ b/src/dhcp/nm-dhcp-systemd.c
@@ -513,7 +513,7 @@ bound4_handle (NMDhcpSystemd *self)
 
 		nm_dhcp_client_set_state (NM_DHCP_CLIENT (self),
 		                          NM_DHCP_STATE_BOUND,
-		                          G_OBJECT (ip4_config),
+		                          NM_IP_CONFIG_CAST (ip4_config),
 		                          options);
 	} else {
 		_LOGW ("%s", error->message);
@@ -822,7 +822,7 @@ bound6_handle (NMDhcpSystemd *self)
 	if (ip6_config) {
 		nm_dhcp_client_set_state (NM_DHCP_CLIENT (self),
 		                          NM_DHCP_STATE_BOUND,
-		                          G_OBJECT (ip6_config),
+		                          NM_IP_CONFIG_CAST (ip6_config),
 		                          options);
 	} else {
 		_LOGW ("%s", error->message);