diff --git a/src/ikarus.boot b/src/ikarus.boot
index 40f695c..2a12786 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.compiler.ss b/src/ikarus.compiler.ss
index bd2d93c..04bdd9e 100644
--- a/src/ikarus.compiler.ss
+++ b/src/ikarus.compiler.ss
@@ -141,7 +141,7 @@
     [$bignum-byte-set!  3   effect]
     ;;; ratnums
     [$make-ratnum       2   value]
-    [$ratnum?           1   pred]
+    [ratnum?            1   pred]
     [$ratnum-n          1   value]
     [$ratnum-d          1   value]
     ;;; symbols
@@ -1970,7 +1970,7 @@
       [($symbol-string $symbol-unique-string)
        (andmap (check op symbol?) rand*)]
       [($constant-ref $set-constant! $intern $pcb-set! $pcb-ref $make-symbol
-        $make-ratnum $ratnum? $ratnum-n $ratnum-d
+        $make-ratnum ratnum? $ratnum-n $ratnum-d
         $symbol-value $set-symbol-value! $set-symbol-function! $symbol-plist $set-symbol-plist!
         $set-symbol-system-value! $set-symbol-system-value!
         $set-symbol-unique-string!
@@ -3260,7 +3260,7 @@
      [(symbol?)    
       (indirect-type-pred vector-mask vector-tag #f
          symbol-record-tag rand* Lt Lf ac)]
-     [($ratnum?)    
+     [(ratnum?)    
       (indirect-type-pred vector-mask vector-tag #f
          ratnum-tag rand* Lt Lf ac)]
      [(procedure?) (type-pred closure-mask closure-tag rand* Lt Lf ac)]
@@ -4131,7 +4131,7 @@
        $set-port-output-index! $set-port-output-size!) 
       (do-effect-prim op arg*
         (cons (movl (int void-object) eax) ac))]
-     [(fixnum? bignum? flonum? immediate? $fxzero? boolean? char? pair? 
+     [(fixnum? bignum? flonum? ratnum? immediate? $fxzero? boolean? char? pair? 
        vector? bytevector? string? symbol?
        procedure? null? not eof-object? $fx= $fx< $fx<= $fx> $fx>= eq?
        $char= $char< $char<= $char> $char>= $unbound-object? code?
diff --git a/src/ikarus.numerics.ss b/src/ikarus.numerics.ss
index 49bcc25..e339b2f 100644
--- a/src/ikarus.numerics.ss
+++ b/src/ikarus.numerics.ss
@@ -27,17 +27,21 @@
 
 
 (library (ikarus generic-arithmetic)
-  (export + - * zero? = < <= > >= add1 sub1 quotient remainder
+  (export + - * / zero? = < <= > >= add1 sub1 quotient remainder
           positive? expt
           quotient+remainder number->string string->number)
   (import 
     (ikarus system $fx)
+    (ikarus system $ratnums)
+    (ikarus system $bignums)
     (ikarus system $chars)
     (ikarus system $strings)
-    (except (ikarus) + - * zero? = < <= > >= add1 sub1 quotient
+    (except (ikarus) + - * / zero? = < <= > >= add1 sub1 quotient
             remainder quotient+remainder number->string positive?
             string->number expt))
 
+  ;(define (ratnum? c) #f)
+
   (define (fixnum->flonum x)
     (foreign-call "ikrt_fixnum_to_flonum" x))
   (define (bignum->flonum x)
@@ -266,7 +270,28 @@
       [(x y) (binary/ x y)]
       [(x) 
        (cond
+         [(fixnum? x)
+          (cond
+            [($fxzero? x) (error '/ "division by 0")]
+            [($fx> x 0)
+             (if ($fx= x 1)
+                 1
+                 ($make-ratnum 1 x))]
+            [else
+             (if ($fx= x -1)
+                 -1
+                 ($make-ratnum -1 (- x)))])]
+         [(bignum? x)
+          (if ($bignum-positive? x)
+              ($make-ratnum 1 x)
+              ($make-ratnum -1 (- x)))]
          [(flonum? x) (foreign-call "ikrt_fl_invert" x)]
+         [(ratnum? x)
+          (let ([n ($ratnum-n x)] [d ($ratnum-d x)])
+            (cond
+              [($fx= n 1) d]
+              [($fx= n -1) (- d)]
+              [else ($make-ratnum d n)]))]
          [else (error '/ "unspported argument ~s" x)])]
       [(x y z . rest)
        (let f ([a (binary/ x y)] [b z] [ls rest])
@@ -380,13 +405,21 @@
     (lambda (x)
       (utf8-bytevector->string
         (foreign-call "ikrt_bignum_to_bytevector" x))))
-
+  
+  (define ratnum->string
+    (lambda (x) 
+      (string-append 
+        (number->string ($ratnum-n x))
+        "/"
+        (number->string ($ratnum-d x)))))
+  
   (define number->string
     (lambda (x)
       (cond
         [(fixnum? x) (fixnum->string x)]
         [(bignum? x) (bignum->string x)]
         [(flonum? x) (flonum->string x)]
+        [(ratnum? x) (ratnum->string x)]
         [else (error 'number->string "~s is not a number" x)])))
 
   (define modulo
diff --git a/src/ikarus.predicates.ss b/src/ikarus.predicates.ss
index d5b29a7..f2b3bd5 100644
--- a/src/ikarus.predicates.ss
+++ b/src/ikarus.predicates.ss
@@ -1,14 +1,14 @@
 
 (library (ikarus predicates)
 
-  (export fixnum? flonum? bignum? number? complex? real? rational?
+  (export fixnum? flonum? bignum? ratnum? number? complex? real? rational?
           integer? exact? eof-object? bwp-object? immediate?
           boolean? char? vector? bytevector? string? procedure? null? pair?
           symbol? code? not weak-pair? eq? eqv? equal?) 
 
   (import 
 
-    (except (ikarus) fixnum? flonum? bignum? number? complex? real?
+    (except (ikarus) fixnum? flonum? bignum? ratnum? number? complex? real?
             rational? integer? exact? eof-object? bwp-object?
             immediate? boolean? char? vector? bytevector? string? procedure?
             null? pair? weak-pair? symbol? code? not eq? eqv? equal?
@@ -18,13 +18,14 @@
     (ikarus system $chars)
     (ikarus system $strings)
     (ikarus system $vectors)
-    (rename (only (ikarus) fixnum? flonum? bignum? eof-object?
+    (rename (only (ikarus) fixnum? flonum? bignum? ratnum? eof-object?
                   bwp-object? immediate? boolean? char? vector? string?
                   bytevector? procedure? null? pair? symbol? code? eq?
                   port? input-port? output-port?)
             (fixnum? sys:fixnum?)
             (flonum? sys:flonum?)
             (bignum? sys:bignum?)
+            (ratnum? sys:ratnum?)
             (eof-object? sys:eof-object?)
             (bwp-object? sys:bwp-object?)
             (immediate? sys:immediate?)
@@ -50,6 +51,9 @@
   (define bignum? 
     (lambda (x) (sys:bignum? x)))
   
+  (define ratnum? 
+    (lambda (x) (sys:ratnum? x)))
+  
   (define flonum? 
     (lambda (x) (sys:flonum? x)))
   
@@ -57,7 +61,8 @@
     (lambda (x)
       (or (sys:fixnum? x)
           (sys:bignum? x)
-          (sys:flonum? x))))
+          (sys:flonum? x)
+          (sys:ratnum? x))))
   
   (define complex?
     (lambda (x) (number? x)))
@@ -70,6 +75,7 @@
       (cond
         [(sys:fixnum? x) #t]
         [(sys:bignum? x) #t]
+        [(sys:ratnum? x) #t]
         [(sys:flonum? x) #f]
         [else (error 'rational? "~s is not a number" x)])))
 
@@ -78,6 +84,7 @@
       (cond
         [(sys:fixnum? x) #t]
         [(sys:bignum? x) #t]
+        [(sys:ratnum? x) #f]
         [(sys:flonum? x) (error 'integer "dunno for ~s" x)]
         [else #f])))
 
diff --git a/src/makefile.ss b/src/makefile.ss
index 6bdb47b..080cc80 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -362,12 +362,14 @@
     [>=                      i r]
     [zero?                   i r]
     [*                       i r]
+    [/                       i r]
     [+                       i r]
     [add1                    i]
     [sub1                    i]
     [expt                    i]
     [number?                 i r]
     [bignum?                 i]
+    [ratnum?                 i]
     [integer?                i]
     [flonum?                 i]
     [positive?               i r]
@@ -550,7 +552,6 @@
     [$make-ratnum       $rat]
     [$ratnum-n          $rat]
     [$ratnum-d          $rat]
-    [$ratnum?           $rat]
 
     [$make-vector       $vectors]
     [$vector-length     $vectors]