diff --git a/racket/src/cify/arg.rkt b/racket/src/cify/arg.rkt
index 13dc35aa62..1b79429020 100644
--- a/racket/src/cify/arg.rkt
+++ b/racket/src/cify/arg.rkt
@@ -36,16 +36,19 @@
        [precise-cases?
         ;; Get full arity to record for arity reporting
         (define idss unsorted-idss)
+        (define (bytes->string-constant s)
+          ;; Drop the leading `#`:
+          (substring (format "~s" s) 1))
+        (define (encode big-endian?)
+          (bytes->string-constant 
+           (apply bytes-append
+                  ;; Encode individual arities as pairs of `int`s:
+                  (for/list ([ids (in-list idss)])
+                    (define-values (min-a max-a) (lambda-arity `(lambda ,ids)))
+                    (bytes-append (integer->integer-bytes min-a 4 #t big-endian?)
+                                  (integer->integer-bytes max-a 4 #t big-endian?))))))
         (values (- (+ (length idss) 1))
-                (substring
-                 (format "~s"
-                         (apply bytes-append
-                                ;; Encode individual arities as pairs of little-endian `int`s:
-                                (for/list ([ids (in-list idss)])
-                                  (define-values (min-a max-a) (lambda-arity `(lambda ,ids)))
-                                  (bytes-append (integer->integer-bytes min-a 4 #t #f)
-                                                (integer->integer-bytes max-a 4 #t #f)))))
-                 1))]
+                (format "c_SELECT_LITTLE_BIG_ENDIAN(~a, ~a)" (encode #f) (encode #t)))]
        [else
         ;; Get approximate arity for predictions about calls
         (define idss (sort unsorted-idss < #:key args-length))
diff --git a/racket/src/racket/src/port.c b/racket/src/racket/src/port.c
index 063e3d8d41..b0d11aa8ab 100644
--- a/racket/src/racket/src/port.c
+++ b/racket/src/racket/src/port.c
@@ -33,6 +33,10 @@
 #include "schmach.h"
 #include "schrktio.h"
 #include <errno.h>
+#ifdef OS_X
+/* needed for old gcc to define `off_t` */
+# include <unistd.h>
+#endif
 #ifndef DONT_IGNORE_PIPE_SIGNAL
 # include <signal.h>
 #endif
diff --git a/racket/src/racket/src/startup-glue.inc b/racket/src/racket/src/startup-glue.inc
index f691335c97..dd2986dc88 100644
--- a/racket/src/racket/src/startup-glue.inc
+++ b/racket/src/racket/src/startup-glue.inc
@@ -66,8 +66,13 @@ static void c_pop_mark_stack(c_saved_mark_stack_t s)
 }
 #endif
 
-#define c_use_fuel() if (DECREMENT_FUEL(c_scheme_fuel_counter, 1) <= 0) scheme_out_of_fuel();
+#ifdef SCHEME_BIG_ENDIAN
+# define c_SELECT_LITTLE_BIG_ENDIAN(l, b) b
+#else
+# define c_SELECT_LITTLE_BIG_ENDIAN(l, b) l
+#endif
 
+#define c_use_fuel() if (DECREMENT_FUEL(c_scheme_fuel_counter, 1) <= 0) scheme_out_of_fuel();
 
 #define c_RUNSTACK_INIT_VAL NULL
 
@@ -212,20 +217,12 @@ static Scheme_Object *c_wrong_arity(const char *name, int argc, Scheme_Object **
   return NULL;
 }
 
-static mzshort *convert_arities(int mina, const char *a)
-{
-  /* FIXME: On a big-endian machine, we need to reverse the byte order in arities */
-  return (mzshort *)a;
-}
-
 static Scheme_Object *scheme_make_prim_w_case_arity(Scheme_Prim *prim, const char *name, mzshort mina, const char *arities)
 {
   Scheme_Object *p;
-  mzshort *a;
   p = scheme_make_prim_w_arity(prim, name, 0, 0);
   ((Scheme_Primitive_Proc *)p)->mina = mina;
-  a = convert_arities(mina, arities);
-  ((Scheme_Primitive_Proc *)p)->mu.cases = a;
+  ((Scheme_Primitive_Proc *)p)->mu.cases = (mzshort *)arities;
   return p;
 }
 
@@ -235,11 +232,9 @@ static Scheme_Object *scheme_make_prim_closure_w_case_arity(Scheme_Primitive_Clo
                                                             mzshort mina, const char *arities)
 {
   Scheme_Object *p;
-  mzshort *a;
   p = scheme_make_prim_closure_w_arity(prim, size, vals, name, 0, 0);
   ((Scheme_Primitive_Proc *)p)->mina = mina;
-  a = convert_arities(mina, arities);
-  ((Scheme_Primitive_Proc *)p)->mu.cases = a;
+  ((Scheme_Primitive_Proc *)p)->mu.cases = (mzshort *)arities;
   return p;
 }