diff --git a/Makefile.am b/Makefile.am
index 8953a009afc65c4cd8842e6b42f6558d51e658e0..23795966e27ba97b7fcf80698c182eb97859ef53 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -24,11 +24,11 @@ pkgdata_DATA = $(DEMO).tar.gz
 demo-tarball: $(DEMO).tar.gz
 
 $(DEMO).tar.gz: $(DEMO)
-	$(TAR) cf - $(DEMO) | $(GZIP) -9 > $@
+	$(TAR_PROGRAM) cf - $(DEMO) | $(GZIP_PROGRAM) -9 > $@
 
 $(DEMO): DEMO
 	mkdir $@ ; cd $@ ; \
-	( cd ../DEMO ; $(TAR) cf - . ) | $(TAR) xf -
+	( cd ../DEMO ; $(TAR_PROGRAM) cf - . ) | $(TAR_PROGRAM) xf -
 	rm -f $@/src/[0-9]d/Makefile.in
 
 clean-local:
diff --git a/configure.ac b/configure.ac
index 7fd5e1876d964b767280080c7aab0eaa29525d0c..0d074a97a39ae2c070e4c140c01f590eba76757b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ(2.52)
-AC_INIT([alberta], [1.2-pre4], [claus@mathematik.uni-freiburg.de])
+AC_INIT([alberta], [1.2-pre6], [claus@mathematik.uni-freiburg.de])
 
 AC_CONFIG_SRCDIR([ALBERTA/src/Common/alberta.h])
 AM_MAINTAINER_MODE
@@ -38,8 +38,8 @@ AC_PREFIX_DEFAULT([`pwd`])
 # Checks for programs.
 AC_PROG_INSTALL
 AC_PROG_LN_S
-AC_CHECK_PROGS([GZIP],[gzip])
-AC_CHECK_PROGS([TAR],[gtar tar])
+AC_CHECK_PROGS([GZIP_PROGRAM],[gzip])
+AC_CHECK_PROGS([TAR_PROGRAM],[gtar tar])
 
 # Compiler characteristics
 dnl