diff -r 9885f6be80f0 -r 6e71ffc71972 Makefile
--- a/Makefile	Mon Nov 28 01:09:15 2011 +0200
+++ b/Makefile	Mon Nov 28 01:09:29 2011 +0200
@@ -22,9 +22,9 @@
 ################################################################
 # Build tool definition/switches.
 
-RST2HTML = rst2html
+RST2HTML := rst2html
 ifeq '$(host_os)' 'cygwin'
-  RST2HTML = rst2html.py
+  RST2HTML := rst2html.py
 endif
 
 RST_WARNING_FLAGS := --halt warning