diff --git a/README.md b/README.md
index 53b94abcc..792ac2b7c 100644
--- a/README.md
+++ b/README.md
@@ -29,11 +29,11 @@ irc.mozilla.org.
 
 ### Browser Extensions
 
-#### Firefox
+#### Firefox and Seamonkey
 
-PDF.js is built into version 19+ of Firefox, however one extension is still available:
+PDF.js is built into version 19+ of Firefox, however the extension is still available:
 
-+ [Development Version](http://mozilla.github.io/pdf.js/extensions/firefox/pdf.js.xpi) - This version is updated every time new code is merged into the PDF.js codebase. This should be quite stable but still might break from time to time.
++ [Development Version](http://mozilla.github.io/pdf.js/extensions/firefox/pdf.js.xpi) - This version is updated every time new code is merged into the PDF.js codebase. This should be quite stable but still might break from time to time. This version is also reported to work when installed as extension in Seamonkey 2.39.
 
 #### Chrome and Opera