diff --git a/README b/README
index ee98eba..acfd3d4 100644
--- a/README
+++ b/README
@@ -55,6 +55,19 @@ MAGIC
 	The ``magic'' make(1) targets attempt to use pkg-config(1) for
 	libraries and their flags.
 
+ENVIRONMENT VARIABLES
+
+	``DESTDIR''
+		The destination directory for `install', normally blank.
+
+	``PREFIX''
+		The installation prefix, normally "/usr/local".
+
+	``MANDIR''
+		The man-page sub-directory, normally "man".
+		On some systems it should be set to "share/man".
+
+
 PREPROCESSOR DEFINES
 
 	``BUFFER_SIZE''