diff --git a/modules/33acrossBidAdapter.js b/modules/33acrossBidAdapter.js
index 8fec4415733..497cf9f7110 100644
--- a/modules/33acrossBidAdapter.js
+++ b/modules/33acrossBidAdapter.js
@@ -28,7 +28,13 @@ function _createBidResponse(response) {
 }
 
 function _isViewabilityMeasurable() {
-  return !isIframe() && utils.getWindowTop().document.visibilityState === 'visible';
+  return !_isIframe();
+}
+
+function _getViewability(element, topWin, { w, h } = {}) {
+  return utils.getWindowTop().document.visibilityState === 'visible'
+    ? _getPercentInView(element, topWin, { w, h })
+    : 0;
 }
 
 // Infer the necessary data from valid bid for a minimal ttxRequest and create HTTP request
@@ -41,7 +47,7 @@ function _createServerRequest(bidRequest, gdprConsent) {
   const minSize = _getMinSize(sizes);
 
   const viewabilityAmount = _isViewabilityMeasurable()
-    ? _getPercentInView(element, utils.getWindowTop(), minSize)
+    ? _getViewability(element, utils.getWindowTop(), minSize)
     : NON_MEASURABLE;
 
   const contributeViewability = ViewabilityContributor(viewabilityAmount);
@@ -221,7 +227,7 @@ function ViewabilityContributor(viewabilityAmount) {
   return contributeViewability;
 }
 
-function isIframe() {
+function _isIframe() {
   try {
     return utils.getWindowSelf() !== utils.getWindowTop();
   } catch (e) {
diff --git a/test/spec/modules/33acrossBidAdapter_spec.js b/test/spec/modules/33acrossBidAdapter_spec.js
index 1fffcd7f55c..c8f0421e1e6 100644
--- a/test/spec/modules/33acrossBidAdapter_spec.js
+++ b/test/spec/modules/33acrossBidAdapter_spec.js
@@ -337,9 +337,9 @@ describe('33acrossBidAdapter:', function () {
     });
 
     context('when tab is inactive', function() {
-      it('returns \'nm\'', function() {
+      it('returns 0', function() {
         const ttxRequest = new TtxRequestBuilder()
-          .withViewabiliuty({amount: spec.NON_MEASURABLE})
+          .withViewabiliuty({amount: 0})
           .build();
         const serverRequest = new ServerRequestBuilder()
           .withData(ttxRequest)