diff --git a/src/backends/meta-monitor-config-manager.c b/src/backends/meta-monitor-config-manager.c
index 84ea04faa..f712e9c9a 100644
--- a/src/backends/meta-monitor-config-manager.c
+++ b/src/backends/meta-monitor-config-manager.c
@@ -1275,7 +1275,8 @@ create_for_switch_config_all_mirror (MetaMonitorConfigManager *config_manager)
       .height = height
     },
     .scale = best_scale,
-    .monitor_configs = monitor_configs
+    .monitor_configs = monitor_configs,
+    .is_primary = TRUE,
   };
 
   logical_monitor_configs = g_list_append (NULL, logical_monitor_config);