diff --git a/README b/README
index b3254ba..1cbb6d7 100644
--- a/README
+++ b/README
@@ -7,3 +7,17 @@ See the COPYING file for licensing terms.
 This software is distributed from the following site:
 
   http://www.pogo.org.uk/~mark/bpm-tools/
+
+The build is controlled via Makefile variables. In general
+you should be able to build using:
+
+  $ make
+  $ make install
+
+To change the target prefix, for example:
+
+  $ make install PREFIX=/opt/bpm-tools
+
+The Makefile picks up additional variables from a .config file
+in the source directory. You will prefer to use this if you want
+to control build flags for testing and debugging.