diff --git a/mes/module/mes/boot-0.scm b/mes/module/mes/boot-0.scm
index f0bd8bac..767a1f28 100644
--- a/mes/module/mes/boot-0.scm
+++ b/mes/module/mes/boot-0.scm
@@ -136,6 +136,9 @@
       (if (null? (cdr rest)) (car rest)
           (append2 (car rest) (apply append (cdr rest))))))
 
+(if (not (defined? '%datadir))
+    (module-define! (current-module) '%datadir "mes"))
+
 (define %moduledir (string-append %datadir "/module/"))
 
 (include (string-append %moduledir "mes/type-0.mes"))
diff --git a/module/mescc.scm b/module/mescc.scm
index cf4db42c..dae7316c 100644
--- a/module/mescc.scm
+++ b/module/mescc.scm
@@ -37,10 +37,10 @@
   (define-macro (mes-use-module . rest) #t)))
 
 (define %host-arch (or (getenv "%arch") %arch))
-(define %prefix (getenv "%prefix"))
-(define %includedir (getenv "%includedir"))
-(define %libdir (getenv "%libdir"))
-(define %version (getenv "%version"))
+(define %prefix (or (getenv "%prefix") "mes"))
+(define %includedir (or (getenv "%includedir") "include"))
+(define %libdir (or (getenv "%libdir") "."))
+(define %version (or (getenv "%version") "0.0"))
 (define %numbered-arch? (and=> (getenv "%numbered_arch") (lambda (x) (equal? x "true"))))
 
 (when (and=> (getenv "V") (lambda (v) (and (= (string-length v) 1) (> (string->number v) 1))))
@@ -183,3 +183,5 @@ General help using GNU software: <http://gnu.org/gethelp/>
           (compile? (mescc:compile options))
           (assemble? (mescc:assemble options))
           (else (mescc:link options)))))
+
+(define main mescc:main)