diff --git a/Makefile.am b/Makefile.am
index 875f498..4bbe8f3 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -56,8 +56,8 @@
 
 xmlConf.sh: xmlConf.sh.in Makefile
 ## Use sed and then mv to avoid problems if the user interrupts.
-	sed -e 's,\@XML_LIBDIR\@,$(XML_LIBDIR),g' \
-	    -e 's,\@XML_INCLUDEDIR\@,$(XML_INCLUDEDIR),g' \
-	    -e 's,\@XML_LIBS\@,$(XML_LIBS),g' \
+	sed -e 's?\@XML_LIBDIR\@?$(XML_LIBDIR)?g' \
+	    -e 's?\@XML_INCLUDEDIR\@?$(XML_INCLUDEDIR)?g' \
+	    -e 's?\@XML_LIBS\@?$(XML_LIBS)?g' \
 	      < $(srcdir)/xmlConf.sh.in > xmlConf.tmp \
 	  && mv xmlConf.tmp xmlConf.sh