diff --git a/services/abonemments/AbonemmentService.js b/services/abonemments/AbonemmentService.js
index 79e1b82..dd1c46d 100644
--- a/services/abonemments/AbonemmentService.js
+++ b/services/abonemments/AbonemmentService.js
@@ -92,6 +92,14 @@ class AbonemmentService {
     const normalizedRecipientEmail = this.normalizeEmail(recipientEmail);
     const forSelf = isForSelf !== false && !normalizedRecipientEmail;
 
+    if (typeof signingCity !== 'string' || signingCity.trim() === '') {
+      throw new Error('signingCity is required');
+    }
+
+    if (typeof signatureDataUrl !== 'string' || signatureDataUrl.trim() === '') {
+      throw new Error('signatureDataUrl is required');
+    }
+
     if (!forSelf && !normalizedRecipientEmail) {
       throw new Error('recipient_email is required when subscription is for another person');
     }
@@ -349,6 +357,14 @@ class AbonemmentService {
     const normalizedRecipientEmail = this.normalizeEmail(recipientEmail);
     console.log('[SUBSCRIBE] Normalized recipient email:', normalizedRecipientEmail); // NEW
 
+    if (typeof signingCity !== 'string' || signingCity.trim() === '') {
+      throw new Error('signingCity is required');
+    }
+
+    if (typeof signatureDataUrl !== 'string' || signatureDataUrl.trim() === '') {
+      throw new Error('signatureDataUrl is required');
+    }
+
     if (coffeeId === undefined || coffeeId === null) throw new Error('coffeeId is required');
 
     const hasRecipientFields = recipientName || normalizedRecipientEmail || recipientNotes;