diff --git a/src/auction.js b/src/auction.js
index 9052d6fd7a8..6dd0432712f 100644
--- a/src/auction.js
+++ b/src/auction.js
@@ -914,6 +914,7 @@ export function getStandardBidderSettings(mediaType, bidderCode) {
       }
     }
   }
+
   return standardSettings;
 }
 
@@ -965,7 +966,7 @@ function setKeys(keyValues, bidderSettings, custBidObj, bidReq) {
 
     if (
       ((typeof bidderSettings.suppressEmptyKeys !== 'undefined' && bidderSettings.suppressEmptyKeys === true) ||
-      key === CONSTANTS.TARGETING_KEYS.DEAL) && // hb_deal is suppressed automatically if not set
+      key === CONSTANTS.TARGETING_KEYS.DEAL || key === CONSTANTS.TARGETING_KEYS.ACAT) && // hb_deal & hb_acat are suppressed automatically if not set
       (
         isEmptyStr(value) ||
         value === null ||
diff --git a/test/spec/auctionmanager_spec.js b/test/spec/auctionmanager_spec.js
index 5ddf3ebf75e..6a72da8edce 100644
--- a/test/spec/auctionmanager_spec.js
+++ b/test/spec/auctionmanager_spec.js
@@ -232,6 +232,15 @@ describe('auctionmanager.js', function () {
       assert.deepEqual(response, expected);
     });
 
+    it('should suppress acat if undefined', function () {
+      const noAcatBid = deepClone(DEFAULT_BID);
+      noAcatBid.meta.primaryCatId = ''
+      let expected = getDefaultExpected(noAcatBid);
+      delete expected.hb_acat;
+      let response = getKeyValueTargetingPairs(noAcatBid.bidderCode, noAcatBid);
+      assert.deepEqual(response, expected);
+    });
+
     it('No bidder level configuration defined - default for video', function () {
       config.setConfig({
         cache: {