diff --git a/alembic/versions/2b1743f77436_cascade_deleting_flags_when_tokens_are_.py b/alembic/versions/2b1743f77436_cascade_deleting_flags_when_tokens_are_.py
new file mode 100644
index 0000000..1c11995
--- /dev/null
+++ b/alembic/versions/2b1743f77436_cascade_deleting_flags_when_tokens_are_.py
@@ -0,0 +1,46 @@
+"""Cascade deleting flags when tokens are deleted
+
+Revision ID: 2b1743f77436
+Revises: 5993f9240bcf
+Create Date: 2019-01-16 13:38:34.954904
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '2b1743f77436'
+down_revision = '5993f9240bcf'
+
+
+def upgrade():
+    """ Remove the existing foreign key in pull_request_flags.token_id and
+    re-create it with CASCADE on delete and update.
+    """
+    # alter the constraints
+    op.drop_constraint('pull_request_flags_token_id_fkey', 'pull_request_flags')
+    op.create_foreign_key(
+        u'pull_request_flags_token_id_fkey',
+        'pull_request_flags',
+        'tokens',
+        ['token_id'],
+        ['id'],
+        ondelete="CASCADE",
+        onupdate="CASCADE",
+    )
+
+
+def downgrade():
+    """ Remove the existing foreign key in pull_request_flags.token_id and
+    re-create it with without specifying the behavior on delete and update.
+    """
+    op.drop_constraint('pull_request_flags_token_id_fkey', 'pull_request_flags')
+    op.create_foreign_key(
+        u'pull_request_flags_token_id_fkey',
+        'pull_request_flags',
+        'tokens',
+        ['token_id'],
+        ['id'],
+    )
diff --git a/pagure/lib/model.py b/pagure/lib/model.py
index 793da43..ac8e148 100644
--- a/pagure/lib/model.py
+++ b/pagure/lib/model.py
@@ -2293,7 +2293,9 @@ class PullRequestFlag(BASE):
         nullable=False,
     )
     token_id = sa.Column(
-        sa.String(64), sa.ForeignKey("tokens.id"), nullable=True
+        sa.String(64),
+        sa.ForeignKey("tokens.id", ondelete="CASCADE", onupdate="CASCADE"),
+        nullable=True
     )
     status = sa.Column(sa.String(32), nullable=False)
     user_id = sa.Column(