diff --git a/migrations/versions/0014_preserve_task_due_times.py b/migrations/versions/0014_preserve_task_due_times.py
new file mode 100644
index 0000000..c3a6a25
--- /dev/null
+++ b/migrations/versions/0014_preserve_task_due_times.py
@@ -0,0 +1,31 @@
+"""preserve time flags for existing task deadlines
+
+Revision ID: 0014_preserve_task_due_times
+Revises: 0013_task_due_has_time
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0014_preserve_task_due_times"
+down_revision = "0013_task_due_has_time"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    tasks = sa.table(
+        "tasks",
+        sa.column("due_at", sa.DateTime(timezone=True)),
+        sa.column("due_has_time", sa.Boolean()),
+    )
+    op.execute(
+        tasks.update()
+        .where(tasks.c.due_at.is_not(None))
+        .where(sa.extract("hour", tasks.c.due_at) != 23)
+        .values(due_has_time=True)
+    )
+
+
+def downgrade() -> None:
+    pass