diff --git a/build-aux/pre-inst-env.in b/build-aux/pre-inst-env.in
index efc134f5..da9c61c0 100644
--- a/build-aux/pre-inst-env.in
+++ b/build-aux/pre-inst-env.in
@@ -18,10 +18,12 @@
 # You should have received a copy of the GNU General Public License
 # along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
 
-srcdir="@srcdir@"
 abs_top_srcdir="@abs_top_srcdir@"
+export abs_top_srcdir
 abs_top_builddir="@abs_top_builddir@"
+export abs_top_builddir
 prefix=${prefix-@prefix@}
+export prefix
 program_prefix=${program_prefix-@program_prefix@}
 
 MES_PREFIX=${MES_PREFIX-${abs_top_srcdir}/mes}
diff --git a/lib/tests/posix/50-open-read.c b/lib/tests/posix/50-open-read.c
index 2b955b09..7e7ff0b8 100644
--- a/lib/tests/posix/50-open-read.c
+++ b/lib/tests/posix/50-open-read.c
@@ -30,9 +30,12 @@ main (int argc, char const *argv[])
 {
   eputs ("test:getenv\n");
   char file_name[PATH_MAX];
-  char *srcdir = getenv ("srcdir");
-  if (!srcdir)
-    return 1;
+  char *srcdir = getenv ("abs_top_srcdir");
+  if (! srcdir) // for running by hand
+    srcdir = ".";
+  eputs ("srcdir=");
+  eputs (srcdir);
+  eputs ("\n");
   strcpy (file_name, srcdir);
   strcpy (file_name + strlen (srcdir), "/lib/tests/posix/data/open-read");
   eputs ("test open:");
@@ -40,13 +43,13 @@ main (int argc, char const *argv[])
   eputs ("\n");
   int filedes = open (file_name, 0, 0);
   if (filedes <= 2)
-    return 2;
+    return 1;
   char buf[20];
   int n = read (filedes, buf, sizeof (buf));
   if (n != 5)
-    return 3;
+    return 2;
   if (strcmp (buf, "hello"))
-    return 4;
+    return 3;
   eputs ("test read: ");
   eputs (buf);
   eputs ("\n");