diff --git a/ghost/members-api/lib/repositories/member/index.js b/ghost/members-api/lib/repositories/member/index.js
index 98134f86c3..bd276779ab 100644
--- a/ghost/members-api/lib/repositories/member/index.js
+++ b/ghost/members-api/lib/repositories/member/index.js
@@ -80,6 +80,10 @@ module.exports = class MemberRepository {
 
         const memberData = _.pick(data, ['email', 'name', 'note', 'subscribed', 'geolocation', 'created_at', 'products']);
 
+        if (memberData.products && memberData.products.length > 1) {
+            throw new errors.BadRequestError(tpl(messages.moreThanOneProduct));
+        }
+
         const member = await this._Member.add({
             ...memberData,
             labels
@@ -128,6 +132,10 @@ module.exports = class MemberRepository {
             const existingProductIds = existingProducts.map(product => product.id);
             const incomingProductIds = data.products.map(product => product.id);
 
+            if (incomingProductIds.length > 1 && incomingProductIds.length > existingProductIds.length) {
+                throw new errors.BadRequestError(tpl(messages.moreThanOneProduct));
+            }
+
             const productsToAdd = _.differenceWith(incomingProductIds, existingProductIds);
             const productsToRemove = _.differenceWith(existingProductIds, incomingProductIds);
             const productsToModify = productsToAdd.concat(productsToRemove);