diff --git a/db/migrate/20240611093449_convert_signature_id_to_bigint.rb b/db/migrate/20240611093449_convert_signature_id_to_bigint.rb
new file mode 100644
index 000000000..420497e4a
--- /dev/null
+++ b/db/migrate/20240611093449_convert_signature_id_to_bigint.rb
@@ -0,0 +1,19 @@
+class ConvertSignatureIdToBigint < ActiveRecord::Migration[7.1]
+  def up
+    change_column :signatures, :id, :bigint
+    change_column :archived_signatures, :id, :bigint
+    change_column :signatures, :petition_id, :bigint
+    change_column :archived_signatures, :petition_id, :bigint
+    change_column :signatures, :invalidation_id, :bigint
+    change_column :archived_signatures, :invalidation_id, :bigint
+  end
+
+  def down
+    change_column :signatures, :id, :integer
+    change_column :archived_signatures, :id, :integer
+    change_column :signatures, :petition_id, :integer
+    change_column :archived_signatures, :petition_id, :integer
+    change_column :signatures, :invalidation_id, :integer
+    change_column :archived_signatures, :invalidation_id, :integer
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index e35c8b398..d0f7b5abb 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2024_06_11_085936) do
+ActiveRecord::Schema[7.1].define(version: 2024_06_11_093449) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "intarray"
   enable_extension "plpgsql"
@@ -198,13 +198,13 @@
     t.index ["petition_id"], name: "index_archived_rejections_on_petition_id", unique: true
   end
 
-  create_table "archived_signatures", id: :serial, force: :cascade do |t|
+  create_table "archived_signatures", force: :cascade do |t|
     t.string "name", limit: 255, null: false
     t.string "state", limit: 20, default: "pending", null: false
     t.string "perishable_token", limit: 255
     t.string "postcode", limit: 255
     t.string "ip_address", limit: 20
-    t.integer "petition_id"
+    t.bigint "petition_id"
     t.datetime "created_at", precision: nil
     t.datetime "updated_at", precision: nil
     t.boolean "notify_by_email", default: false
@@ -215,7 +215,7 @@
     t.integer "number"
     t.string "location_code", limit: 30
     t.datetime "invalidated_at", precision: nil
-    t.integer "invalidation_id"
+    t.bigint "invalidation_id"
     t.datetime "government_response_email_at", precision: nil
     t.datetime "debate_scheduled_email_at", precision: nil
     t.datetime "debate_outcome_email_at", precision: nil
@@ -639,13 +639,13 @@
     t.index ["petition_id"], name: "index_rejections_on_petition_id", unique: true
   end
 
-  create_table "signatures", id: :serial, force: :cascade do |t|
+  create_table "signatures", force: :cascade do |t|
     t.string "name", limit: 255, null: false
     t.string "state", limit: 20, default: "pending", null: false
     t.string "perishable_token", limit: 255
     t.string "postcode", limit: 255
     t.string "ip_address", limit: 20
-    t.integer "petition_id"
+    t.bigint "petition_id"
     t.datetime "created_at", precision: nil
     t.datetime "updated_at", precision: nil
     t.boolean "notify_by_email", default: false
@@ -657,7 +657,7 @@
     t.boolean "seen_signed_confirmation_page", default: false, null: false
     t.string "location_code", limit: 30
     t.datetime "invalidated_at", precision: nil
-    t.integer "invalidation_id"
+    t.bigint "invalidation_id"
     t.datetime "government_response_email_at", precision: nil
     t.datetime "debate_scheduled_email_at", precision: nil
     t.datetime "debate_outcome_email_at", precision: nil