diff --git a/src/adapters/lifestreet.js b/src/adapters/lifestreet.js
index eceecb54608..a28b2da7e0c 100644
--- a/src/adapters/lifestreet.js
+++ b/src/adapters/lifestreet.js
@@ -92,12 +92,14 @@ const LifestreetAdapter = function LifestreetAdapter() {
           } catch (e) {
             return;
           }
-          if (object.message && object.message === PREBID_REQUEST_MESSAGE && object.slotName) {
+          if (object.message && object.message === PREBID_REQUEST_MESSAGE && object.slotName &&
+              window.$$PREBID_GLOBAL$$[object.slotName]) {
             ev.source.postMessage(JSON.stringify({
               message: PREBID_RESPONSE_MESSAGE,
               slotObject: window.$$PREBID_GLOBAL$$[object.slotName]
             }), '*');
             window.$$PREBID_GLOBAL$$[object.slotName].destroy();
+            window.$$PREBID_GLOBAL$$[object.slotName] = null;
           }
         }, false);
       } else {