diff --git a/README.md b/README.md
index 34a5819..a208b6e 100644
--- a/README.md
+++ b/README.md
@@ -213,6 +213,11 @@ cloned_env["CPPPATH"] << "three"
 * lowercase symbols - Rscons options
 * lowercase strings - reserved as user-defined construction variables
 
+### API documentation
+
+Documentation for the complete Rscons API can be found at
+http://rubydoc.info/github/holtrop/rscons/frames.
+
 ## Contributing
 
 1. Fork it