diff --git a/src/_zkapauthorizer/schema.py b/src/_zkapauthorizer/schema.py
index fc078c2a102f75decc5a21db4592468bf5e3f1e7..66583d408617bf15142733dba5c71bc65375a892 100644
--- a/src/_zkapauthorizer/schema.py
+++ b/src/_zkapauthorizer/schema.py
@@ -131,4 +131,11 @@ _UPGRADES = {
         ALTER TABLE [vouchers] ADD COLUMN [public-key] text
         """,
     ],
+
+    2: [
+        """
+        -- Keep track of progress through redemption of each voucher.
+        ALTER TABLE [vouchers] ADD COLUMN [counter] integer
+        """,
+    ],
 }