diff --git a/atst/domain/environments.py b/atst/domain/environments.py
index ace75a3a..41824dc5 100644
--- a/atst/domain/environments.py
+++ b/atst/domain/environments.py
@@ -1,4 +1,4 @@
-from sqlalchemy import text
+from sqlalchemy import text, func, or_
 from sqlalchemy.orm.exc import NoResultFound
 from sqlalchemy.orm import load_only
 from typing import List
@@ -104,6 +104,12 @@ class Environments(object):
             .join(CLIN)
             .filter(CLIN.start_date <= now)
             .filter(CLIN.end_date > now)
+            .filter(
+                or_(
+                    Environment.claimed_until == None,
+                    Environment.claimed_until <= func.now(),
+                )
+            )
             # select only these columns
             .options(load_only("id", "creator_id"))
         )
diff --git a/atst/models/utils.py b/atst/models/utils.py
index bde09c91..a3df73e3 100644
--- a/atst/models/utils.py
+++ b/atst/models/utils.py
@@ -28,7 +28,7 @@ def claim_for_update(resource, minutes=30):
         .filter(
             and_(
                 Model.id == resource.id,
-                or_(Model.claimed_until == None, Model.claimed_until < func.now()),
+                or_(Model.claimed_until == None, Model.claimed_until <= func.now()),
             )
         )
         .update({"claimed_until": claim_until}, synchronize_session="fetch")