diff --git a/scheme/ikarus.boot.prebuilt b/scheme/ikarus.boot.prebuilt
index d2800ca..6345995 100644
Binary files a/scheme/ikarus.boot.prebuilt and b/scheme/ikarus.boot.prebuilt differ
diff --git a/scheme/ikarus.numerics.ss b/scheme/ikarus.numerics.ss
index 3df5830..214b725 100644
--- a/scheme/ikarus.numerics.ss
+++ b/scheme/ikarus.numerics.ss
@@ -590,20 +590,37 @@
 
   (define binary-bitwise-xor
     (lambda (x y)
+      (define (fxbn x y)
+        (let ([y0 (bitwise-and y (greatest-fixnum))]
+              [y1 (bitwise-arithmetic-shift-right y (- (fixnum-width) 1))])
+          (bitwise-ior
+            ($fxlogand ($fxlogxor x y0) (greatest-fixnum))
+            (bitwise-arithmetic-shift-left
+              (bitwise-arithmetic-shift-right
+                (if ($fx>= x 0) y (bitwise-not y))
+                (- (fixnum-width) 1))
+              (- (fixnum-width) 1)))))
+      (define (bnbn x y)
+        (let ([x0 (bitwise-and x (greatest-fixnum))]
+              [x1 (bitwise-arithmetic-shift-right x (- (fixnum-width) 1))]
+              [y0 (bitwise-and y (greatest-fixnum))]
+              [y1 (bitwise-arithmetic-shift-right y (- (fixnum-width) 1))])
+          (bitwise-ior
+            ($fxlogand ($fxlogxor x0 y0) (greatest-fixnum))
+            (bitwise-arithmetic-shift-left
+              (binary-bitwise-xor x1 y1)
+              (- (fixnum-width) 1)))))
       (cond
         [(fixnum? x)
          (cond
            [(fixnum? y) ($fxlogxor x y)]
-           [(bignum? y)
-            (foreign-call "ikrt_fxbnlogxor" x y)]
+           [(bignum? y) (fxbn x y)]
            [else 
             (die 'bitwise-xor "not an exact integer" y)])]
         [(bignum? x)
          (cond
-           [(fixnum? y)
-            (foreign-call "ikrt_fxbnlogxor" y x)]
-           [(bignum? y) 
-            (foreign-call "ikrt_bnbnlogxor" x y)]
+           [(fixnum? y) (fxbn y x)]
+           [(bignum? y) (bnbn x y)]
            [else
             (die 'bitwise-xor "not an exact integer" y)])]
         [else (die 'bitwise-xor "not an exact integer" x)])))
diff --git a/scheme/last-revision b/scheme/last-revision
index 09d2f32..1c61ae4 100644
--- a/scheme/last-revision
+++ b/scheme/last-revision
@@ -1 +1 @@
-1479
+1480
diff --git a/scheme/tests/bitwise-op.ss b/scheme/tests/bitwise-op.ss
index a47c777..7344164 100644
--- a/scheme/tests/bitwise-op.ss
+++ b/scheme/tests/bitwise-op.ss
@@ -74,7 +74,7 @@
   (define (test-other-cases)
     (test-case bitwise-and)
     (test-case bitwise-ior)
-    ;(test-case bitwise-xor)
+    (test-case bitwise-xor)
     )
 
 
diff --git a/src/ikarus-numerics.c b/src/ikarus-numerics.c
index 614cf0f..a0e95ed 100644
--- a/src/ikarus-numerics.c
+++ b/src/ikarus-numerics.c
@@ -1476,20 +1476,6 @@ ikrt_bnbnlogor(ikptr x, ikptr y, ikpcb* pcb){
   }
 }
 
-
-ikptr
-ikrt_fxbnlogxor(ikptr x, ikptr y, ikpcb* pcb){
-  fprintf(stderr, "ikrt_fxbnlogxor\n");
-  exit(-1);
-}
-
-ikptr
-ikrt_bnbnlogxor(ikptr x, ikptr y, ikpcb* pcb){
-  fprintf(stderr, "ikrt_bnbnlogxor\n");
-  exit(-1);
-}
-
-
 static void
 copy_bits_shifting_right(mp_limb_t* src, mp_limb_t* dst, int n, int m){
   mp_limb_t carry = src[0] >> m;