--- wrapper/CMakeLists.txt.orig	2007-12-22 06:20:04.000000000 +0100
+++ wrapper/CMakeLists.txt	2007-12-22 06:23:07.000000000 +0100
@@ -21,7 +21,8 @@
 # we edit the python source to make the opensync.Error class an exception, allowing it to be raised
 # FIXME: find a way (if it exists) of getting SWIG to do this for us
 	ADD_CUSTOM_COMMAND(TARGET ${SWIG_MODULE_opensync_REAL_NAME} POST_BUILD
-	   COMMAND sed ARGS "s/^class Error(object):/class Error(Exception):/" opensync.py > opensync_hack.py
+	   COMMAND cp ARGS -f ${CMAKE_CURRENT_BINARY_DIR}/opensync.py ${CMAKE_CURRENT_BINARY_DIR}/opensync_hack.py
+	   COMMAND sed ARGS -i -e "s/^class Error(object):/class Error(Exception):/" ${CMAKE_CURRENT_BINARY_DIR}/opensync_hack.py
 	   COMMENT "Munging SWIG-generated Python class"
 	   VERBATIM)