diff --git a/scheme/ikarus.boot.prebuilt b/scheme/ikarus.boot.prebuilt
index 396601f..49b2670 100644
Binary files a/scheme/ikarus.boot.prebuilt and b/scheme/ikarus.boot.prebuilt differ
diff --git a/scheme/ikarus.fixnums.ss b/scheme/ikarus.fixnums.ss
index ff39c35..feb7cec 100644
--- a/scheme/ikarus.fixnums.ss
+++ b/scheme/ikarus.fixnums.ss
@@ -26,13 +26,13 @@
           fixnum->string 
           fxarithmetic-shift-left fxarithmetic-shift-right fxarithmetic-shift
           fxmin fxmax
-          error@fx+ error@fx*)
+          error@fx+ error@fx* error@fx-)
   (import 
     (ikarus system $fx)
     (ikarus system $chars)
     (ikarus system $pairs)
     (ikarus system $strings)
-    (prefix (only (ikarus) fx+ fx*) sys:)
+    (prefix (only (ikarus) fx+ fx* fx-) sys:)
     (except (ikarus) fxzero? fxadd1 fxsub1 fxlognot fx+ fx- fx*
             fxquotient fxremainder fxmodulo fxlogor fxlogand
             fxlogxor fxsll fxsra fx= fx< fx<= fx> fx>=
@@ -76,38 +76,29 @@
         (die 'fxnot "not a fixnum" x))
       ($fxlognot x)))
   
-
-  (define error@fx+
+  (define (make-fx-error who msg)
     (lambda (x y) 
       (if (fixnum? x)
           (if (fixnum? y) 
-              (die 'fx+ "overflow when adding numbers" x y)
-              (die 'fx+ "not a fixnum" y))
-          (die 'fx+ "not a fixnum" x))))
+              (die who msg x y)
+              (die who "not a fixnum" y))
+          (die who "not a fixnum" x))))
+
+  (define error@fx+ 
+    (make-fx-error 'fx+ "overflow when adding numbers"))
+  
+  (define error@fx- 
+    (make-fx-error 'fx- "overflow when subtracting numbers"))
 
   (define error@fx*
-    (lambda (x y) 
-      (if (fixnum? x) 
-          (if (fixnum? y) 
-              (die 'fx* "overflow when multiplying numbers" x y)
-              (die 'fx* "not a fixnum" y))
-          (die 'fx* "not a fixnum" x))))
+    (make-fx-error 'fx* "overflow when multiplying numbers"))
 
-  (define fx+ 
-    (lambda (x y) 
-      (sys:fx+ x y)))
+  (define (fx+ x y) (sys:fx+ x y))
 
-  (define fx-
-    (lambda (x y) 
-      (unless (fixnum? x)
-        (die 'fx- "not a fixnum" x))
-      (unless (fixnum? y)
-        (die 'fx- "not a fixnum" y))
-      ($fx- x y)))
+  (define (fx* x y) (sys:fx* x y))
+
+  (define (fx- x y) (sys:fx- x y))
 
-  (define fx*
-    (lambda (x y) 
-      (sys:fx* x y)))
   
 
   (define false-loop
diff --git a/scheme/last-revision b/scheme/last-revision
index e4f0a85..a3d3785 100644
--- a/scheme/last-revision
+++ b/scheme/last-revision
@@ -1 +1 @@
-1379
+1380
diff --git a/scheme/makefile.ss b/scheme/makefile.ss
index 4c24544..9f5139d 100755
--- a/scheme/makefile.ss
+++ b/scheme/makefile.ss
@@ -566,6 +566,7 @@
     [make-traced-procedure                       i]
     [error@fx+                                   ]
     [error@fx*                                   ]
+    [error@fx-                                   ]
     [fasl-write                                  i]
     [lambda                                      i r ba se ne]
     [and                                         i r ba se ne]
diff --git a/scheme/pass-specify-rep-primops.ss b/scheme/pass-specify-rep-primops.ss
index 794412d..36e417f 100644
--- a/scheme/pass-specify-rep-primops.ss
+++ b/scheme/pass-specify-rep-primops.ss
@@ -1247,6 +1247,8 @@
 
 (define-primop fx+ safe
   [(V x y) (cogen-value-+ x y)])
+(define-primop fx- safe
+  [(V x y) (cogen-value-- x y)])
 
 (define-primop fx* safe
   [(V a b) 
diff --git a/scheme/pass-specify-rep.ss b/scheme/pass-specify-rep.ss
index ead91b1..1cb4ff0 100644
--- a/scheme/pass-specify-rep.ss
+++ b/scheme/pass-specify-rep.ss
@@ -56,6 +56,7 @@
   (define (primop-interrupt-handler x)
     (case x
       [(fx+)          'error@fx+]
+      [(fx-)          'error@fx-]
       [(fx*)          'error@fx*]
       [else                    x]))
   (define (make-interrupt-call op args)