diff --git a/appview/db/signup.go b/appview/db/signup.go
--- a/appview/db/signup.go
+++ b/appview/db/signup.go
@@ -5,7 +5,7 @@
 )
 
 func AddInflightSignup(e Execer, signup models.InflightSignup) error {
-	query := `insert into signups_inflight (email, invite_code) values (?, ?)`
+	query := `insert or replace into signups_inflight (email, invite_code) values (?, ?)`
 	_, err := e.Exec(query, signup.Email, signup.InviteCode)
 	return err
 }