diff --git a/models/Survey.json b/models/Survey.json
index 7cd4f44..178ab48 100644
--- a/models/Survey.json
+++ b/models/Survey.json
@@ -22,8 +22,7 @@
     "expiration": {
       "type": "string",
       "format": "date-time",
-      "description": "The date and time when the survey expires. After this date and time, the survey will no longer be available for extraction.",
-      "minimum": 0
+      "description": "The date and time when the survey expires. After this date and time, the survey will no longer be available for extraction."
     },
     "size": {
       "type": "string",