diff --git a/Appendix-D:-References.md b/Appendix-D:-References.md
index 3f6aea3..2bbbf45 100644
--- a/Appendix-D:-References.md
+++ b/Appendix-D:-References.md
@@ -35,5 +35,5 @@ If you would like to submit a resource link to be added to this list, please pos
    * [cvddetails.com](https://www.cvedetails.com/vulnerability-list/vendor_id-452/product_id-3264/Mozilla-Firefox.html) - **h**ttps://www.cvedetails.com/vulnerability-list/vendor_id-452/product_id-3264/Mozilla-Firefox.html
 * [Firefox Site Compatibility](https://www.fxsitecompat.com/en-CA/) - **h**ttps://www.fxsitecompat.com/en-CA/
    * Community-driven Web developer engagement initiative focused on the backward compatibility and regressions in Firefox
-* [Portable Firefox](http://portableapps.com/apps/internet/firefox_portable) - **h**ttp://portableapps.com/apps/internet/firefox_portable
-  * [Stable/ESR Releases](http://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./) - **h**ttp://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./
+* [Portable Firefox](https://portableapps.com/apps/internet/firefox_portable) - **h**ttps://portableapps.com/apps/internet/firefox_portable
+  * [Stable/ESR Releases](https://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./) - **h**ttps://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./