diff --git a/tests/app/public_contracts/schemas/v0/definitions.json b/tests/app/public_contracts/schemas/v0/definitions.json
index fb36b5cb4..7b44b63f2 100644
--- a/tests/app/public_contracts/schemas/v0/definitions.json
+++ b/tests/app/public_contracts/schemas/v0/definitions.json
@@ -4,9 +4,5 @@
   "uuid": {
     "type": "string",
     "pattern": "^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}$"
-  },
-  "datetime": {
-    "type": "string",
-    "format": "date-time"
   }
 }
diff --git a/tests/app/public_contracts/schemas/v0/email_notification.json b/tests/app/public_contracts/schemas/v0/email_notification.json
index 013fb49ff..b1ac4821c 100644
--- a/tests/app/public_contracts/schemas/v0/email_notification.json
+++ b/tests/app/public_contracts/schemas/v0/email_notification.json
@@ -14,19 +14,13 @@
       "type": "string",
       "enum": ["email"]
     },
-    "created_at": {"$ref": "definitions.json#/datetime"},
-    "sent_at": {"oneOf":[
-      {"$ref": "definitions.json#/datetime"},
-      {"type": "null"}
-    ]},
+    "created_at": {"type": "string", "format": "date-time"},
+    "sent_at": {"type": ["string", "null"], "format": "date-time"},
     "sent_by": {"oneOf":[
       {"type": "string"},
       {"type": "null"}
     ]},
-    "updated_at": {"oneOf":[
-      {"$ref": "definitions.json#/datetime"},
-      {"type": "null"}
-    ]},
+    "updated_at": {"type": ["string", "null"], "format": "date-time"},
     "status": {
       "type": "string",
       "enum": [
diff --git a/tests/app/public_contracts/schemas/v0/sms_notification.json b/tests/app/public_contracts/schemas/v0/sms_notification.json
index d81def6ea..5110ad081 100644
--- a/tests/app/public_contracts/schemas/v0/sms_notification.json
+++ b/tests/app/public_contracts/schemas/v0/sms_notification.json
@@ -14,19 +14,13 @@
       "type": "string",
       "enum": ["sms"]
     },
-    "created_at": {"$ref": "definitions.json#/datetime"},
-    "sent_at": {"oneOf":[
-      {"$ref": "definitions.json#/datetime"},
-      {"type": "null"}
-    ]},
+    "created_at": {"type": "string", "format": "date-time"},
+    "sent_at": {"type": ["string", "null"], "format": "date-time"},
     "sent_by": {"oneOf":[
       {"type": "string"},
       {"type": "null"}
     ]},
-    "updated_at": {"oneOf":[
-      {"$ref": "definitions.json#/datetime"},
-      {"type": "null"}
-    ]},
+    "updated_at": {"type": ["string", "null"], "format": "date-time"},
     "status": {
       "type": "string",
       "enum": [