diff --git a/alembic/versions/61ac23e35f86_fix_pr_project_from_key.py b/alembic/versions/61ac23e35f86_fix_pr_project_from_key.py
new file mode 100644
index 0000000..a7bb5b8
--- /dev/null
+++ b/alembic/versions/61ac23e35f86_fix_pr_project_from_key.py
@@ -0,0 +1,54 @@
+"""Fix pr project_from key
+
+Revision ID: 61ac23e35f86
+Revises: 47f5fab6f46a
+Create Date: 2017-12-05 16:59:17.117199
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '61ac23e35f86'
+down_revision = '47f5fab6f46a'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    """ Alter the pull_requests table to update the foreign key to set null
+    on delete.
+    """
+
+    op.drop_constraint(
+        'pull_requests_project_id_from_fkey',
+        'pull_requests',
+        type_='foreignkey')
+    op.create_foreign_key(
+        name='pull_requests_project_id_from_fkey',
+        source_table='pull_requests',
+        referent_table='projects',
+        local_cols=['project_from_id'],
+        remote_cols=['id'],
+        onupdate='cascade',
+        ondelete='set null',
+    )
+
+
+def downgrade():
+    """ Alter the pull_requests table to update the foreign key to cascade
+    on delete.
+    """
+
+    op.drop_constraint(
+        'pull_requests_project_id_from_fkey',
+        'pull_requests',
+        type_='foreignkey')
+    op.create_foreign_key(
+        name='pull_requests_project_id_from_fkey',
+        source_table='pull_requests',
+        referent_table='projects',
+        local_cols=['project_from_id'],
+        remote_cols=['id'],
+        onupdate='cascade',
+        ondelete='cascade',
+    )