diff --git a/isacc_messaging/models/isacc_fhirdate.py b/isacc_messaging/models/isacc_fhirdate.py
index a115adaf..a1eead2a 100644
--- a/isacc_messaging/models/isacc_fhirdate.py
+++ b/isacc_messaging/models/isacc_fhirdate.py
@@ -35,5 +35,5 @@ def __repr__(self):
         return self.isostring
 
 
-DEEP_PAST = IsaccFHIRDate("1975-01-01T00:00:00Z")
-DEEP_FUTURE = IsaccFHIRDate("2025-01-01T00:00:00Z")
+DEEP_PAST = IsaccFHIRDate("1975-01-01")
+DEEP_FUTURE = IsaccFHIRDate("2025-01-01")