diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 268e1b24..71de85f9 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -58,7 +58,7 @@ model Event {
 
 model MailCredentials {
   id        String   @id @default(uuid())
-  userId    String
+  userId    String   @unique
   email     String
   password  String
   host      String