diff --git a/src/_zkapauthorizer/schema.py b/src/_zkapauthorizer/schema.py
index 66583d408617bf15142733dba5c71bc65375a892..e3a37eb2023cfe890fb08a7500fdd519e9335bd0 100644
--- a/src/_zkapauthorizer/schema.py
+++ b/src/_zkapauthorizer/schema.py
@@ -135,7 +135,7 @@ _UPGRADES = {
     2: [
         """
         -- Keep track of progress through redemption of each voucher.
-        ALTER TABLE [vouchers] ADD COLUMN [counter] integer
+        ALTER TABLE [vouchers] ADD COLUMN [counter] integer DEFAULT 0
         """,
     ],
 }