diff --git a/README.md b/README.md
index 8fd7845..bb3e2e5 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,14 @@
 # gerritcp
 A utility to copy changesets from one gerrit instance to another
 
+## usage
+
+    gerritcp -d [dir] -c [config.yaml]
+
+dir specified a directory to keep the git repo in (because it's usually too
+large to keep in RAM), config.yaml points to the configuration for upstream,
+downstream and workstreams.
+
 ## Theory of operation
 The tool is built primarily for the use case of downstreaming coreboot into
 Chromium OS. If feasible, extension of its scope to other scenarios is welcome.