diff --git a/modules/yieldmoBidAdapter.js b/modules/yieldmoBidAdapter.js
index d904791d29a2..b2d13e88c808 100644
--- a/modules/yieldmoBidAdapter.js
+++ b/modules/yieldmoBidAdapter.js
@@ -47,7 +47,7 @@ export const spec = {
       if (userId) {
         const pubcid = userId.pubcid;
         serverRequest.pubcid = pubcid;
-      } else {
+      } else if (request.crumbs) {
         serverRequest.pubcid = request.crumbs.pubcid;
       }
     });
diff --git a/test/spec/modules/yieldmoBidAdapter_spec.js b/test/spec/modules/yieldmoBidAdapter_spec.js
index 80a9265a5c26..12dd87e15176 100644
--- a/test/spec/modules/yieldmoBidAdapter_spec.js
+++ b/test/spec/modules/yieldmoBidAdapter_spec.js
@@ -1,6 +1,6 @@
 import { expect } from 'chai';
 import { spec } from 'modules/yieldmoBidAdapter';
-import {newBidder} from 'src/adapters/bidderFactory';
+import { newBidder } from 'src/adapters/bidderFactory';
 import * as utils from 'src/utils';
 
 describe('YieldmoAdapter', function () {
@@ -50,6 +50,13 @@ describe('YieldmoAdapter', function () {
       expect(request.url).to.be.equal(ENDPOINT);
     });
 
+    it('should not blow up if crumbs is undefined', function () {
+      let bidArray = [
+        { ...bid, crumbs: undefined }
+      ]
+      expect(function () { spec.buildRequests(bidArray) }).not.to.throw()
+    })
+
     it('should place bid information into the p parameter of data', function () {
       let placementInfo = spec.buildRequests(bidArray).data.p;
       expect(placementInfo).to.equal('[{"placement_id":"adunit-code","callback_id":"30b31c1838de1e","sizes":[[300,250],[300,600]]}]');