diff --git a/doc/usage/index.rst b/doc/usage/index.rst
index 2ba8733..28f9683 100644
--- a/doc/usage/index.rst
+++ b/doc/usage/index.rst
@@ -45,6 +45,7 @@
    cmd/fatload
    cmd/fdt
    cmd/for
+   cmd/gpio
    cmd/load
    cmd/loadm
    cmd/loady