diff --git a/src/Vervis/Migration.hs b/src/Vervis/Migration.hs
index 6ccc237..d524e87 100644
--- a/src/Vervis/Migration.hs
+++ b/src/Vervis/Migration.hs
@@ -3019,6 +3019,8 @@ changes hLocal ctx =
         )
         "accept"
         "OutboxItem"
+      -- 548
+    , addUnique' "CollabFulfillsInvite" "Accept" ["accept"]
     ]
 
 migrateDB
diff --git a/th/models b/th/models
index c449e75..bf787ce 100644
--- a/th/models
+++ b/th/models
@@ -592,7 +592,8 @@ CollabFulfillsInvite
     collab CollabId
     accept OutboxItemId
 
-    UniqueCollabFulfillsInvite collab
+    UniqueCollabFulfillsInvite       collab
+    UniqueCollabFulfillsInviteAccept accept
 
 CollabInviterLocal
     collab CollabFulfillsInviteId