diff --git a/lib/spack/spack/main.py b/lib/spack/spack/main.py
index d19578007b4..3d60f5b4eb6 100644
--- a/lib/spack/spack/main.py
+++ b/lib/spack/spack/main.py
@@ -281,7 +281,7 @@ def add_subcommand_group(title, commands):
   spack help --all       list all commands and options
   spack help <command>   help on a specific command
   spack help --spec      help on the package specification syntax
-  spack docs             open http://spack.rtfd.io/ in a browser
+  spack docs             open https://spack.rtfd.io/ in a browser
 """.format(help=section_descriptions['help']))
 
         # determine help from format above