diff --git a/sdk/src/com/appnexus/opensdk/VisibilityDetector.java b/sdk/src/com/appnexus/opensdk/VisibilityDetector.java
index d94f0f16..060531da 100644
--- a/sdk/src/com/appnexus/opensdk/VisibilityDetector.java
+++ b/sdk/src/com/appnexus/opensdk/VisibilityDetector.java
@@ -67,7 +67,7 @@ private boolean remove(List<WeakReference<View>> list, View reference)
         for (Iterator<WeakReference<View>> iterator = list.iterator(); iterator.hasNext(); ) {
             WeakReference<View> weakRef = iterator.next();
             if (weakRef.get() == reference) {
-                if (!(reference instanceof BannerAdView)) {
+                if (reference != null && !(reference instanceof BannerAdView)) {
                     reference.setTag(R.string.native_view_tag, null);
                 }
                 iterator.remove();
diff --git a/sdk/src/com/appnexus/opensdk/utils/ImageService.java b/sdk/src/com/appnexus/opensdk/utils/ImageService.java
index b0fd4c6a..738112dd 100644
--- a/sdk/src/com/appnexus/opensdk/utils/ImageService.java
+++ b/sdk/src/com/appnexus/opensdk/utils/ImageService.java
@@ -74,7 +74,8 @@ public void execute() {
             return;
         }
         if (imageUrlMap != null && !imageUrlMap.isEmpty()) {
-            for (Map.Entry pairs : imageUrlMap.entrySet()) {
+            HashMap<String, String> imageUrlMapCopy = new HashMap<>(imageUrlMap);
+            for (Map.Entry pairs : imageUrlMapCopy.entrySet()) {
                 ImageDownloader downloader = new ImageDownloader(imageReceiver, (String) pairs.getKey(), (String) pairs.getValue(), this);
                 Clog.d(Clog.baseLogTag, "Downloading " + pairs.getKey() + " from url: " + pairs.getValue());
                 downloader.execute();
diff --git a/tests/AppNexusSDKTestApp/app/src/androidTest/java/appnexus/com/appnexussdktestapp/util/Utility.kt b/tests/AppNexusSDKTestApp/app/src/androidTest/java/appnexus/com/appnexussdktestapp/util/Utility.kt
index 03a907d2..05812d70 100644
--- a/tests/AppNexusSDKTestApp/app/src/androidTest/java/appnexus/com/appnexussdktestapp/util/Utility.kt
+++ b/tests/AppNexusSDKTestApp/app/src/androidTest/java/appnexus/com/appnexussdktestapp/util/Utility.kt
@@ -5,7 +5,7 @@ import android.os.Handler
 import android.os.Looper
 import android.util.Log
 import android.view.View
-import java.lang.ref.WeakReference
+import org.junit.Assert
 
 class Utility {
     companion object {
@@ -14,21 +14,26 @@ class Utility {
 
             Handler(Looper.getMainLooper()).post({
                 val vDetector = Class.forName("com.appnexus.opensdk.VisibilityDetector")
-                val create = vDetector.getDeclaredMethod("create", WeakReference::class.java)
-                create.isAccessible = true
-                val weakReference = WeakReference(View(context))
-                val vDetInst = create.invoke(null, weakReference)
+                val getInstance = vDetector.getDeclaredMethod("getInstance")
+                
+                getInstance.isAccessible = true
+                val viewReference = View(context)
+                val vDetInst = getInstance.invoke(null)
 
-                val destroy = vDetector.getDeclaredMethod("destroy", WeakReference::class.java)
+                val addVisibilityListener = vDetector.getDeclaredMethod("addVisibilityListener", View::class.java)
+                addVisibilityListener.isAccessible = true
+                addVisibilityListener.invoke(vDetInst, viewReference)
+
+                val destroy = vDetector.getDeclaredMethod("destroy", View::class.java)
                 destroy.isAccessible = true
-                destroy.invoke(vDetInst, weakReference)
+                destroy.invoke(vDetInst, viewReference)
 
-                val declaredField = vDetector.getDeclaredField("viewListenerMap")
+                val declaredField = vDetector.getDeclaredField("viewList")
                 declaredField.isAccessible = true
-                var map = declaredField.get(vDetInst) as HashMap<Object, Object>
-                Log.e("VISIBILITY", " Size: ${checkZero} ${map.size}");
+                var list = declaredField.get(vDetInst) as List<Object>
+                Log.e("VISIBILITY", " Size: ${checkZero} ${list.size}");
 
-                junit.framework.Assert.assertTrue(map.size == checkZero)
+                Assert.assertEquals(checkZero, list.size)
 
             })
         }
diff --git a/tests/AppNexusSDKTestApp/app/src/main/java/appnexus/com/appnexussdktestapp/MARLoadAndDisplayActivity.kt b/tests/AppNexusSDKTestApp/app/src/main/java/appnexus/com/appnexussdktestapp/MARLoadAndDisplayActivity.kt
index a2682c92..0eec6f22 100644
--- a/tests/AppNexusSDKTestApp/app/src/main/java/appnexus/com/appnexussdktestapp/MARLoadAndDisplayActivity.kt
+++ b/tests/AppNexusSDKTestApp/app/src/main/java/appnexus/com/appnexussdktestapp/MARLoadAndDisplayActivity.kt
@@ -179,7 +179,7 @@ class MARLoadAndDisplayActivity : Activity() {
                     idlingResource.decrement()
             }
 
-            override fun onAdFailed(errorcode: ResultCode, adResponseInfo: ANAdResponseInfo) {
+            override fun onAdFailed(errorcode: ResultCode, adResponseInfo: ANAdResponseInfo?) {
                 msg += "Native Ad Failed:$errorcode\n"
                 toast()
                 if (!idlingResource.isIdleNow)
@@ -313,7 +313,9 @@ class MARLoadAndDisplayActivity : Activity() {
                 onLazyAdLoaded = true
                 arrayListAd.add(adView)
                 if (displayAd)
-                    recyclerListAdView.adapter!!.notifyDataSetChanged()
+                    Handler(Looper.getMainLooper()).post({
+                        recyclerListAdView.adapter!!.notifyDataSetChanged()
+                    })
                 if (!idlingResource.isIdleNow)
                     idlingResource.decrement()
             }