diff --git a/db/booker.js b/db/booker.js
index 99a11d1..56a04ed 100644
--- a/db/booker.js
+++ b/db/booker.js
@@ -8,7 +8,7 @@ const BookerSchema = new mongoose.Schema(
     zip: { type: String, required: true },
     city: { type: String, required: true },
   },
-  { timestamps: true }
+  { timestamps: true, collation: { locale: 'de', strength: 1 } }
 )
 
 export default mongoose.models.Booker || mongoose.model('Booker', BookerSchema)