--- a/doc/src/sgml/Makefile
+++ b/doc/src/sgml/Makefile
@@ -245,7 +245,7 @@
 # if we try to do "make all" in a VPATH build without the explicit
 # $(srcdir) on the postgres.sgml dependency in this rule.  GNU make bug?
 postgres.xml: $(srcdir)/postgres.sgml $(ALMOSTALLSGML)
-	$(OSX) -D. -x lower -i include-xslt-index $< >postgres.xmltmp
+	$(OSX) $(OSXFLAGS) -D. -x lower -i include-xslt-index $< >postgres.xmltmp
 	$(PERL) -p -e 's/\[(aacute|acirc|aelig|agrave|amp|aring|atilde|auml|bull|copy|eacute|egrave|gt|iacute|lt|mdash|nbsp|ntilde|oacute|ocirc|oslash|ouml|pi|quot|scaron|uuml) *\]/\&\1;/gi;' \
 	           -e '$$_ .= qq{<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">\n} if $$. == 1;' \
 	  <postgres.xmltmp > $@