diff --git a/racket/src/cs/bootstrap/constant.rkt b/racket/src/cs/bootstrap/constant.rkt
index 4d6013b204..6d3edcc4af 100644
--- a/racket/src/cs/bootstrap/constant.rkt
+++ b/racket/src/cs/bootstrap/constant.rkt
@@ -25,21 +25,48 @@
                         [(eqv? v v1) rv1]
                         [(eqv? v v2) rv2]
                         [else (error "unknown")]))]
-          [`(define-constant ,id ,v)
-           (when (exact-integer? v)
-             (hash-set! ht id v))]
+          [`(define-constant ,id ,e)
+           (let/cc esc
+             (hash-set! ht id (constant-eval e esc)))]
+          [`(define-constant-default ,id ,e)
+           (hash-ref ht id
+                     (lambda ()
+                       (let/cc esc
+                         (hash-set! ht id (constant-eval e esc)))))]
+          [`(include ,fn)
+           (unless (equal? fn "machine.def")
+             (read-constants-from-file fn))]
           [_ (void)])
         (loop)))))
 
-(when scheme-dir
+(define (constant-eval e esc)
+  (cond
+    [(pair? e)
+     (case (car e)
+       [(if)
+        (if (constant-eval (cadr e) esc)
+            (constant-eval (caddr e) esc)
+            (constant-eval (cadddr e) esc))]
+       [(constant)
+        (hash-ref ht (cadr e) esc)]
+       [(=)
+        (= (constant-eval (cadr e) ht)
+           (constant-eval (caddr e) ht))]
+       [(quote)
+        (cadr e)]
+       [else (esc)])]
+    [else e]))
+
+(define (read-constants-from-file fn)
   (call-with-input-file
-   (build-path scheme-dir "s" (string-append target-machine ".def"))
-   read-constants)
-  
-  (call-with-input-file
-   (build-path scheme-dir "s" "cmacros.ss")
+   (build-path scheme-dir "s" fn)
    read-constants))
 
+(when scheme-dir
+  (read-constants-from-file
+   (string-append target-machine ".def"))
+  (read-constants-from-file "cmacros.ss"))
+
 (define-syntax-rule (define-constant id ...)
   (begin
     (provide id ...)
diff --git a/racket/src/cs/bootstrap/make-boot.rkt b/racket/src/cs/bootstrap/make-boot.rkt
index 3c4bddd9d7..473d15bf3d 100644
--- a/racket/src/cs/bootstrap/make-boot.rkt
+++ b/racket/src/cs/bootstrap/make-boot.rkt
@@ -6,7 +6,8 @@
          (only-in "r6rs-lang.rkt"
                   optimize-level)
          (only-in "scheme-lang.rkt"
-                  current-expand)
+                  current-expand
+                  with-source-path)
          (submod "scheme-lang.rkt" callback)
          "syntax-mode.rkt"
          "r6rs-readtable.rkt"
@@ -206,21 +207,37 @@
      (current-eval
       (let ([e (current-eval)])
         (lambda (stx)
-          (define ex ((current-expand)
-                      (syntax->datum
-                       (let loop ([stx stx])
-                         (syntax-case* stx (#%top-interaction eval-when compile) (lambda (a b)
-                                                                                   (eq? (syntax-e a) (syntax-e b)))
-                           [(#%top-interaction . rest) (loop #'rest)]
-                           [(eval-when (compile) . rest)
-                            #'(eval-when (compile eval load) . rest)]
-                           [_ stx])))))
-          (define r (strip-$app
-                     (strip-$primitive
-                      (if (struct? ex)
-                          ($uncprep ex)
-                          ex))))
-          (e r))))
+          (define (go ex)
+            (define r (strip-$app
+                       (strip-$primitive
+                        (if (struct? ex)
+                            ($uncprep ex)
+                            ex))))
+            (e r))
+          (let loop ([stx stx])
+            (syntax-case* stx (#%top-interaction
+                               eval-when compile
+                               begin
+                               include) (lambda (a b)
+                                          (eq? (syntax-e a) (syntax-e b)))
+              [(#%top-interaction . rest) (loop #'rest)]
+              [(eval-when (compile) . rest)
+               #'(eval-when (compile eval load) . rest)]
+              [(begin e ...)
+               (for-each loop (syntax->list #'(e ...)))]
+              [(include fn)
+               (loop
+                #`(begin #,@(with-source-path 'include (syntax->datum #'fn)
+                              (lambda (n)
+                                (call-with-input-file*
+                                 n
+                                 (lambda (i)
+                                   (let loop ()
+                                     (define r (read-syntax n i))
+                                     (if (eof-object? r)
+                                         '()
+                                         (cons r (loop))))))))))]
+              [_ (go ((current-expand) (syntax->datum stx)))])))))
      (status "Load cmacros using expander")
      (load-ss (build-path scheme-dir "s/cmacros.ss"))
      (status "Continue loading expander")))