diff --git a/README.md b/README.md
index 5da27735..8622f87e 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,10 @@ Likewise, your server(s) will likely need supporting software installed before y
 
 Capistrano is designed to deploy using a single, non-privileged SSH user, using a *non-interactive* SSH session. If your deployment requires `sudo`, interactive prompts, authenticating as one user but running commands as another, you can probably accomplish this with Capistrano, but it may be difficult. Your automated deployments will be much smoother if you can avoid such requirements.
 
+#### Shells
+
+Capistrano 3 expects a POSIX shell like Bash or Sh. Shells like tcsh, csh, and such may work, but probably will not.
+
 ## Quick start
 
 ### Requirements
diff --git a/docs/documentation/upgrading/index.markdown b/docs/documentation/upgrading/index.markdown
index 17ea1ffb..f509bff2 100644
--- a/docs/documentation/upgrading/index.markdown
+++ b/docs/documentation/upgrading/index.markdown
@@ -136,3 +136,7 @@ Capistrano 3 now runs the `deploy:cleanup` task as part of the standard deploy w
 ```ruby
 set :keep_releases, 10
 ```
+
+#### POSIX Shell
+
+Capistrano 3 expects a POSIX shell like Bash or Sh. Shells like tcsh, csh, and such may work, but probably will not.