Index: lang/python-doc-html/Makefile
===================================================================
--- lang/python-doc-html/Makefile
+++ lang/python-doc-html/Makefile
@@ -3,7 +3,7 @@
 PORTNAME=	python-doc-${DOCFORMAT}
 PORTVERSION=	${PYTHON_PORTVERSION}
 CATEGORIES=	lang python
-MASTER_SITES=	PYTHON/ftp/python/doc/${PORTVERSION} \
+MASTER_SITES?=	PYTHON/ftp/python/doc/${PORTVERSION} \
 		PYTHON/ftp/python/doc/current
 DISTNAME=	python-${PORTVERSION}-docs-${DOCFORMAT}
 DIST_SUBDIR=	python
@@ -54,6 +54,7 @@
 .endfor
 .endfor
 MASTER_SITES+=	PYTHON/ftp/python/doc/current
+.export MASTER_SITES
 .endif
 
 pre-install: