diff --git a/src/quota/sql.py b/src/quota/sql.py
index 7579aa3b0..f7e68975d 100644
--- a/src/quota/sql.py
+++ b/src/quota/sql.py
@@ -38,7 +38,7 @@
     UPDATE quota_limits
        SET available=available+?, revoked_at=datetime('now')
      WHERE subject=?
-       AND revoked_at < datetime('now', ?);
+       AND datetime(revoked_at, ?) <= datetime('now');
     """
 
 
@@ -54,7 +54,7 @@
     UPDATE quota_limits
        SET available=?, revoked_at=datetime('now')
      WHERE subject=?
-       AND revoked_at < datetime('now', ?);
+       AND datetime(revoked_at, ?) <= datetime('now');
     """
 
 INIT_QUOTA_PG = """
diff --git a/src/runners/quota_scheduler.py b/src/runners/quota_scheduler.py
index ac7a8cd22..3d260b07b 100644
--- a/src/runners/quota_scheduler.py
+++ b/src/runners/quota_scheduler.py
@@ -217,7 +217,8 @@ def quota_revocation(
 
     subject_id = get_subject_id(quota_limiter.type)
 
-    if quota_limiter.quota_increase is not None:
+    # do not update quota revocation date when the increase is set to zero
+    if quota_limiter.quota_increase is not None and quota_limiter.quota_increase > 0:
         increase_quota(
             connection,
             increase_quota_statement,
@@ -226,6 +227,7 @@ def quota_revocation(
             quota_limiter.period,
         )
 
+    # do not update quota revocation date when the initial quota is set to zero
     if quota_limiter.initial_quota is not None and quota_limiter.initial_quota > 0:
         reset_quota(
             connection,