diff --git a/app/src/main/java/org/fdroid/fdroid/FDroidApp.java b/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
index d3f0b58ce..b28b637b8 100644
--- a/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
+++ b/app/src/main/java/org/fdroid/fdroid/FDroidApp.java
@@ -279,7 +279,11 @@ public class FDroidApp extends Application {
                         new FileNameGenerator() {
                             @Override
                             public String generate(String imageUri) {
-                                return imageUri.substring(imageUri.lastIndexOf('/') + 1);
+                                if (TextUtils.isEmpty(imageUri)) {
+                                    return "null";
+                                } else {
+                                    return imageUri.substring(imageUri.lastIndexOf('/') + 1);
+                                }
                             }
                         },
                         // 30 days in secs: 30*24*60*60 = 2592000
diff --git a/app/src/main/java/org/fdroid/fdroid/NotificationHelper.java b/app/src/main/java/org/fdroid/fdroid/NotificationHelper.java
index 40fba8548..9871c7b52 100644
--- a/app/src/main/java/org/fdroid/fdroid/NotificationHelper.java
+++ b/app/src/main/java/org/fdroid/fdroid/NotificationHelper.java
@@ -18,6 +18,7 @@ import android.support.v4.content.ContextCompat;
 import android.support.v4.content.LocalBroadcastManager;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;
+import android.text.TextUtils;
 import android.text.style.StyleSpan;
 import android.view.View;
 
@@ -494,7 +495,9 @@ class NotificationHelper {
     private Bitmap getLargeIconForEntry(AppUpdateStatusManager.AppUpdateStatus entry) {
         final Point largeIconSize = getLargeIconSize();
         Bitmap iconLarge = null;
-        if (entry.status == AppUpdateStatusManager.Status.Downloading || entry.status == AppUpdateStatusManager.Status.Installing) {
+        if (TextUtils.isEmpty(entry.app.iconUrl)) {
+            return null;
+        } else if (entry.status == AppUpdateStatusManager.Status.Downloading || entry.status == AppUpdateStatusManager.Status.Installing) {
             Bitmap bitmap = Bitmap.createBitmap(largeIconSize.x, largeIconSize.y, Bitmap.Config.ARGB_8888);
             Canvas canvas = new Canvas(bitmap);
             Drawable downloadIcon = ContextCompat.getDrawable(context, R.drawable.ic_notification_download);