diff --git a/src/data/projInfo-schema.json b/src/data/projInfo-schema.json
index e24931f..2565f5a 100644
--- a/src/data/projInfo-schema.json
+++ b/src/data/projInfo-schema.json
@@ -66,6 +66,8 @@
             "items": {
                 "type": "string"
             },
+            "minItems": 1,
+            "uniqueItems": true,
             "description": "The list of initial tabs to display on new saves. This value must have at least one element. Each element should be the ID of the layer to display in that tab."
         },
         "maxTickLength": {