diff --git a/guile/mescc.scm b/guile/mescc.scm
index f4eae8bc..83afbd9e 100755
--- a/guile/mescc.scm
+++ b/guile/mescc.scm
@@ -1,11 +1,11 @@
 #! /bin/sh
 # -*-scheme-*-
 GODIR=${GODIR-@GODIR@}
-MODULEDIR=${MODULEDIR-@MODULEDIR@}
+GUILEDIR=${GUILEDIR-@GUILEDIR@}
 [ "$GODIR" = @"GODIR"@ ] && GODIR=guile
-[ "$MODULEDIR" = @"MODULEDIR"@ ] && MODULEDIR=guile
+[ "$GUILEDIR" = @"GUILEDIR"@ ] && GUILEDIR=guile
 export GUILE_AUTO_COMPILE=${GUILE_AUTO_COMPILE-0}
-exec ${GUILE-guile} -L $MODULEDIR -C $GODIR -e '(mescc)' -s "$0" "$@"
+exec ${GUILE-guile} -L $GUILEDIR -C $GODIR -e '(mescc)' -s "$0" "$@"
 !#
 
 ;;; Mes --- The Maxwell Equations of Software
diff --git a/make/install.make b/make/install.make
index 7428ee2c..5f391a4a 100644
--- a/make/install.make
+++ b/make/install.make
@@ -31,8 +31,10 @@ DATADIR:=$(PREFIX)/share
 DOCDIR:=$(DATADIR)/doc
 endif
 LIBDIR:=$(PREFIX)/lib
-MODULEDIR:=$(PREFIX)/share/guile/site/$(GUILE_EFFECTIVE_VERSION)
+
 GODIR:=$(LIBDIR)/guile/$(GUILE_EFFECTIVE_VERSION)/site-ccache
+GUILEDIR:=$(PREFIX)/share/guile/site/$(GUILE_EFFECTIVE_VERSION)
+MODULEDIR:=$(DATADIR)/module
 
 .tarball-version: tree-clean-p
 	echo $(COMMIT) > $@
@@ -74,6 +76,7 @@ install: $(CLEAN) ChangeLog
 	    -e 's,@DATADIR@,$(DATADIR)/,g' \
 	    -e 's,@DOCDIR@,$(DOCDIR)/,g' \
 	    -e 's,@GODIR@,$(GODIR)/,g' \
+	    -e 's,@GUILEDIR@,$(GUILEDIR)/,g' \
 	    -e 's,@MODULEDIR@,$(MODULEDIR)/,g' \
 	    -e 's,@PREFIX@,$(PREFIX)/,g' \
 	    -e 's,@VERSION@,$(VERSION),g' \
@@ -90,9 +93,9 @@ install: $(CLEAN) ChangeLog
 	$(GIT_ARCHIVE_HEAD) doc \
 		| tar -C $(DESTDIR)$(DOCDIR) --strip=1 -xf-
 	cp ChangeLog $(DESTDIR)$(DOCDIR)
-	mkdir -p $(DESTDIR)$(MODULEDIR)
+	mkdir -p $(DESTDIR)$(GUILEDIR)
 	tar -cf- -C module $(INSTALL_SCM_FILES:module/%=%)\
-		| tar -C $(DESTDIR)$(MODULEDIR) -xf-
+		| tar -C $(DESTDIR)$(GUILEDIR) -xf-
 	mkdir -p $(DESTDIR)$(GODIR)
 	tar -cf- -C module $(INSTALL_GO_FILES:module/%=%)\
 		| tar -C $(DESTDIR)$(GODIR) -xf-
diff --git a/src/mes.c b/src/mes.c
index 617f0c0c..266d2ff4 100644
--- a/src/mes.c
+++ b/src/mes.c
@@ -1248,7 +1248,7 @@ load_env (SCM a) ///((internal))
 {
   r0 = a;
   g_stdin = open ("module/mes/read-0.mes", O_RDONLY);
-  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "mes/read-0.mes", O_RDONLY);
+  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "/mes/read-0.mes", O_RDONLY);
   if (!g_function) r0 = mes_builtins (r0);
   r2 = read_input_file_env (r0);
   g_stdin = STDIN;
@@ -1261,11 +1261,11 @@ bload_env (SCM a) ///((internal))
 #if __MESC__
   char *mo = "mes/read-0-32.mo";
   g_stdin = open ("module/mes/read-0-32.mo", O_RDONLY);
-  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "mes/read-0-32.mo", O_RDONLY);
+  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "/mes/read-0-32.mo", O_RDONLY);
 #else
   char *mo ="mes/read-0.mo";
   g_stdin = open ("module/mes/read-0.mo", O_RDONLY);
-  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "mes/read-0.mo", O_RDONLY);
+  g_stdin = g_stdin >= 0 ? g_stdin : open (MODULEDIR "/mes/read-0.mo", O_RDONLY);
 #endif
 
   if (g_stdin < 0) {eputs ("no such file: ");eputs (mo);eputs ("\n");return 1;}