diff --git a/modules/openxBidAdapter.js b/modules/openxBidAdapter.js
index ef60d6e1856..7be1023450f 100644
--- a/modules/openxBidAdapter.js
+++ b/modules/openxBidAdapter.js
@@ -75,7 +75,7 @@ export const spec = {
 };
 
 function isVideoRequest(bidRequest) {
-  return utils.deepAccess(bidRequest, 'mediaTypes.video') || bidRequest.mediaType === VIDEO;
+  return (utils.deepAccess(bidRequest, 'mediaTypes.video') && !utils.deepAccess(bidRequest, 'mediaTypes.banner')) || bidRequest.mediaType === VIDEO;
 }
 
 function createBannerBidResponses(oxResponseObj, {bids, startTime}) {
diff --git a/test/spec/modules/openxBidAdapter_spec.js b/test/spec/modules/openxBidAdapter_spec.js
index 0fda846faa1..cf8f4f8d62b 100644
--- a/test/spec/modules/openxBidAdapter_spec.js
+++ b/test/spec/modules/openxBidAdapter_spec.js
@@ -178,6 +178,41 @@ describe('OpenxAdapter', function () {
       });
     });
 
+    describe('when request is for a multiformat ad', function () {
+      describe('and request config uses mediaTypes video and banner', () => {
+        const multiformatBid = {
+          bidder: 'openx',
+          params: {
+            unit: '12345678',
+            delDomain: 'test-del-domain'
+          },
+          adUnitCode: 'adunit-code',
+          mediaTypes: {
+            banner: {
+              sizes: [[300, 250]]
+            },
+            video: {
+              playerSize: [300, 250]
+            }
+          },
+          bidId: '30b31c1838de1e',
+          bidderRequestId: '22edbae2733bf6',
+          auctionId: '1d1a030790a475',
+          transactionId: '4008d88a-8137-410b-aa35-fbfdabcb478e'
+        };
+        it('should return true multisize when required params found', function () {
+          expect(spec.isBidRequestValid(multiformatBid)).to.equal(true);
+        });
+
+        it('should send bid request to openx url via GET, with mediaType specified as banner', function () {
+          const request = spec.buildRequests([multiformatBid]);
+          expect(request[0].url).to.equal(`//${multiformatBid.params.delDomain}${URLBASE}`);
+          expect(request[0].data.ph).to.be.undefined;
+          expect(request[0].method).to.equal('GET');
+        });
+      });
+    });
+
     describe('when request is for a video ad', function () {
       describe('and request config uses mediaTypes', () => {
         const videoBidWithMediaTypes = {