diff --git a/coderd/database/migrations/000356_enforce_deadline_below_max_deadline.up.sql b/coderd/database/migrations/000356_enforce_deadline_below_max_deadline.up.sql
index bcb3ab643521f..00c36ddd0b5dd 100644
--- a/coderd/database/migrations/000356_enforce_deadline_below_max_deadline.up.sql
+++ b/coderd/database/migrations/000356_enforce_deadline_below_max_deadline.up.sql
@@ -8,13 +8,15 @@ UPDATE
 SET
     deadline = max_deadline
 WHERE
-    deadline > max_deadline
-    AND max_deadline != '0001-01-01 00:00:00+00';
+    (deadline = '0001-01-01 00:00:00+00'::timestamptz OR deadline > max_deadline)
+    AND max_deadline != '0001-01-01 00:00:00+00'::timestamptz;
 
 -- Add the new constraint.
 ALTER TABLE workspace_builds
     ADD CONSTRAINT workspace_builds_deadline_below_max_deadline
         CHECK (
+            -- (deadline is not zero AND deadline <= max_deadline)...
             (deadline != '0001-01-01 00:00:00+00'::timestamptz AND deadline <= max_deadline)
+            -- UNLESS max_deadline is zero.
             OR max_deadline = '0001-01-01 00:00:00+00'::timestamptz
         );