diff --git a/NewHorizons/Schemas/body_schema.json b/NewHorizons/Schemas/body_schema.json
index c4fe13eb..02771c9b 100644
--- a/NewHorizons/Schemas/body_schema.json
+++ b/NewHorizons/Schemas/body_schema.json
@@ -134,7 +134,10 @@
     },
     "extras": {
       "type": "object",
-      "description": "Extra data that may be used by extension mods"
+      "description": "Extra data that may be used by extension mods",
+      "additionalProperties": {
+        "type": "object"
+      }
     }
   },
   "definitions": {
diff --git a/NewHorizons/Schemas/star_system_schema.json b/NewHorizons/Schemas/star_system_schema.json
index 54770b00..d8073db0 100644
--- a/NewHorizons/Schemas/star_system_schema.json
+++ b/NewHorizons/Schemas/star_system_schema.json
@@ -77,7 +77,10 @@
     },
     "extras": {
       "type": "object",
-      "description": "Extra data that may be used by extension mods"
+      "description": "Extra data that may be used by extension mods",
+      "additionalProperties": {
+        "type": "object"
+      }
     }
   },
   "definitions": {