diff --git a/README.md b/README.md
index be67f7a..f85032d 100644
--- a/README.md
+++ b/README.md
@@ -103,7 +103,7 @@ Args and environment variables can be tailored to a specific build phase by addi
 There may be times where feature detection plus flags just aren't enough.  As an example, you may wish to configure and run multiple processes.
 
 * `--instructions=path` - a dockerfile fragment to be inserted into the final document.
-* `--migration=cmd` - a replacement (generally a script) for `db:prepare`/`db:migrate`.
+* `--migrate=cmd` - a replacement (generally a script) for `db:prepare`/`db:migrate`.
 * `--no-gemfile-updates` - do not modify my gemfile.
 * `--procfile=path` - a [Procfile](https://github.com/ddollar/foreman#foreman) to use in place of launching Rails directly.