diff --git a/libnm-util/nm-setting-bluetooth.c b/libnm-util/nm-setting-bluetooth.c
index 6a2fed74ff..52f0b81e96 100644
--- a/libnm-util/nm-setting-bluetooth.c
+++ b/libnm-util/nm-setting-bluetooth.c
@@ -104,7 +104,7 @@ NMSetting *nm_setting_bluetooth_new (void)
 const char *
 nm_setting_bluetooth_get_connection_type (NMSettingBluetooth *setting)
 {
-	g_return_val_if_fail (NM_IS_SETTING_BLUETOOTH (setting), 0);
+	g_return_val_if_fail (NM_IS_SETTING_BLUETOOTH (setting), NULL);
 
 	return NM_SETTING_BLUETOOTH_GET_PRIVATE (setting)->type;
 }
diff --git a/libnm-util/nm-setting-bond.c b/libnm-util/nm-setting-bond.c
index fe874abef6..421d452aea 100644
--- a/libnm-util/nm-setting-bond.c
+++ b/libnm-util/nm-setting-bond.c
@@ -111,7 +111,7 @@ nm_setting_bond_new (void)
 const char *
 nm_setting_bond_get_interface_name (NMSettingBond *setting)
 {
-	g_return_val_if_fail (NM_IS_SETTING_BOND (setting), 0);
+	g_return_val_if_fail (NM_IS_SETTING_BOND (setting), NULL);
 
 	return NM_SETTING_BOND_GET_PRIVATE (setting)->interface_name;
 }
diff --git a/libnm-util/nm-setting-ip6-config.c b/libnm-util/nm-setting-ip6-config.c
index 45e3e6350c..67c101dc11 100644
--- a/libnm-util/nm-setting-ip6-config.c
+++ b/libnm-util/nm-setting-ip6-config.c
@@ -149,7 +149,7 @@ nm_setting_ip6_config_get_dns (NMSettingIP6Config *setting, guint32 i)
 	NMSettingIP6ConfigPrivate *priv;
 	
 
-	g_return_val_if_fail (NM_IS_SETTING_IP6_CONFIG (setting), 0);
+	g_return_val_if_fail (NM_IS_SETTING_IP6_CONFIG (setting), NULL);
 
 	priv = NM_SETTING_IP6_CONFIG_GET_PRIVATE (setting);
 	g_return_val_if_fail (i <= g_slist_length (priv->dns), NULL);
@@ -631,7 +631,7 @@ nm_setting_ip6_config_get_may_fail (NMSettingIP6Config *setting)
 NMSettingIP6ConfigPrivacy
 nm_setting_ip6_config_get_ip6_privacy (NMSettingIP6Config *setting)
 {
-	g_return_val_if_fail (NM_IS_SETTING_IP6_CONFIG (setting), FALSE);
+	g_return_val_if_fail (NM_IS_SETTING_IP6_CONFIG (setting), NM_SETTING_IP6_CONFIG_PRIVACY_UNKNOWN);
 
 	return NM_SETTING_IP6_CONFIG_GET_PRIVATE (setting)->ip6_privacy;
 }
@@ -1210,8 +1210,8 @@ nm_ip6_address_compare (NMIP6Address *address, NMIP6Address *other)
 const struct in6_addr *
 nm_ip6_address_get_address (NMIP6Address *address)
 {
-	g_return_val_if_fail (address != NULL, 0);
-	g_return_val_if_fail (address->refcount > 0, 0);
+	g_return_val_if_fail (address != NULL, NULL);
+	g_return_val_if_fail (address->refcount > 0, NULL);
 
 	return &address->address;
 }
@@ -1279,8 +1279,8 @@ nm_ip6_address_set_prefix (NMIP6Address *address, guint32 prefix)
 const struct in6_addr *
 nm_ip6_address_get_gateway (NMIP6Address *address)
 {
-	g_return_val_if_fail (address != NULL, 0);
-	g_return_val_if_fail (address->refcount > 0, 0);
+	g_return_val_if_fail (address != NULL, NULL);
+	g_return_val_if_fail (address->refcount > 0, NULL);
 
 	return &address->gateway;
 }
@@ -1427,8 +1427,8 @@ nm_ip6_route_compare (NMIP6Route *route, NMIP6Route *other)
 const struct in6_addr *
 nm_ip6_route_get_dest (NMIP6Route *route)
 {
-	g_return_val_if_fail (route != NULL, 0);
-	g_return_val_if_fail (route->refcount > 0, 0);
+	g_return_val_if_fail (route != NULL, NULL);
+	g_return_val_if_fail (route->refcount > 0, NULL);
 
 	return &route->dest;
 }
@@ -1496,8 +1496,8 @@ nm_ip6_route_set_prefix (NMIP6Route *route, guint32 prefix)
 const struct in6_addr *
 nm_ip6_route_get_next_hop (NMIP6Route *route)
 {
-	g_return_val_if_fail (route != NULL, 0);
-	g_return_val_if_fail (route->refcount > 0, 0);
+	g_return_val_if_fail (route != NULL, NULL);
+	g_return_val_if_fail (route->refcount > 0, NULL);
 
 	return &route->next_hop;
 }