diff --git a/browser/base/content/browser-thumbnails.js b/browser/base/content/browser-thumbnails.js
index 3c37cc7625b..eb5cdac3898 100644
--- a/browser/base/content/browser-thumbnails.js
+++ b/browser/base/content/browser-thumbnails.js
@@ -98,6 +98,9 @@ let gBrowserThumbnails = {
   },
 
   _shouldCapture: function Thumbnails_shouldCapture(aBrowser) {
+    if (gPrivateBrowsingUI.privateBrowsingEnabled)
+      return false;
+
     let doc = aBrowser.contentDocument;
 
     // FIXME Bug 720575 - Don't capture thumbnails for SVG or XML documents as