diff --git a/toolkit/components/thumbnails/content/backgroundPageThumbsContent.js b/toolkit/components/thumbnails/content/backgroundPageThumbsContent.js
index 61386de5fdc..800768106ec 100644
--- a/toolkit/components/thumbnails/content/backgroundPageThumbsContent.js
+++ b/toolkit/components/thumbnails/content/backgroundPageThumbsContent.js
@@ -108,8 +108,6 @@ const backgroundPageThumbsContent = {
           this._startNextCapture();
         }
         else if (this._state == STATE_CANCELED) {
-          // A capture request was received while the current capture's page
-          // was still loading.
           delete this._currentCapture;
           this._startNextCapture();
         }
@@ -119,9 +117,20 @@ const backgroundPageThumbsContent = {
         // The requested page has loaded.  Capture it.
         this._state = STATE_CAPTURING;
         this._captureCurrentPage();
-      } else {
+      }
+      else if (this._state != STATE_CANCELED) {
+        // Something went wrong.  Cancel the capture.  Loading about:blank
+        // while onStateChange is still on the stack does not actually stop
+        // the request if it redirects, so do it asyncly.
         this._state = STATE_CANCELED;
-        this._loadAboutBlank();
+        if (!this._cancelTimer) {
+          this._cancelTimer =
+            Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+          this._cancelTimer.init(() => {
+            this._loadAboutBlank();
+            delete this._cancelTimer;
+          }, 0, Ci.nsITimer.TYPE_ONE_SHOT);
+        }
       }
     }
   },