diff --git a/extension/extension.js b/extension/extension.js
--- a/extension/extension.js
+++ b/extension/extension.js
@@ -566,6 +566,7 @@
             } else if (favIconUrl.match(/^data:image/)) {
                 // Already a data URL
                 filteredTabs[currentIndex].favIconData = favIconUrl;
+                filteredTabs[currentIndex].favIconUrl = "";
                 sendTabsIfComplete();
             } else {
                 // Send a request to fill the cache (=no timeout)