diff --git a/api.v1.json b/api.v1.json
index a5cbecb..318836a 100644
--- a/api.v1.json
+++ b/api.v1.json
@@ -1118,10 +1118,17 @@
             "$ref": "#/components/schemas/controller_id"
           },
           "active_schedule": {
-            "$ref": "#/components/schemas/schedule_simple"
+            "nullable": true,
+            "description": "NULL when unknown (usually because controller is not connected)",
+            "allOf": [
+              {
+                "$ref": "#/components/schemas/schedule_simple"
+              }
+            ]
           },
           "override_schedule": {
             "nullable": true,
+            "description": "NULL when unknown (usually because controller is not connected)",
             "allOf": [
               {
                 "$ref": "#/components/schemas/schedule_simple"
@@ -1298,4 +1305,4 @@
       }
     }
   }
-}
\ No newline at end of file
+}