diff --git a/src/ikarus.boot b/src/ikarus.boot
index b0a1af2..bfce399 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.singular-objects.ss b/src/ikarus.singular-objects.ss
index 01890da..15ae05f 100644
--- a/src/ikarus.singular-objects.ss
+++ b/src/ikarus.singular-objects.ss
@@ -1,15 +1,20 @@
 
 (library (ikarus singular-objects)
-  (export base-rtd eof-object void #;fixnum-width)
+  (export base-rtd eof-object void fixnum-width least-fixnum
+          greatest-fixnum)
   (import 
     (rename (ikarus system $records) (base-rtd sys:base-rtd))
     (rename (ikarus)
             (void sys:void)
-           #; (fixnum-width sys:fixnum-width)
+            (fixnum-width sys:fixnum-width)
+            (least-fixnum sys:least-fixnum)
+            (greatest-fixnum sys:greatest-fixnum)
             (eof-object sys:eof-object)))
 
   (define (void) (sys:void))
-#;  (define (fixnum-width) (sys:fixnum-width))
+  (define (fixnum-width) (sys:fixnum-width))
+  (define (least-fixnum) (sys:least-fixnum))
+  (define (greatest-fixnum) (sys:greatest-fixnum))
   (define (eof-object) (sys:eof-object))
   (define (base-rtd) (sys:base-rtd)))
 
diff --git a/src/makefile.ss b/src/makefile.ss
index 2cc1f32..ee2b39b 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -459,7 +459,9 @@
     [fxarithmetic-shift       i]
     [fxmin       i]
     [fxmax       i]
-    [fixnum-width i]
+    [fixnum-width    i]
+    [least-fixnum    i]
+    [greatest-fixnum i]
 
     [for-each                i r]
     [map                     i r]
diff --git a/src/pass-specify-rep-primops.ss b/src/pass-specify-rep-primops.ss
index 85d4125..2150792 100644
--- a/src/pass-specify-rep-primops.ss
+++ b/src/pass-specify-rep-primops.ss
@@ -545,14 +545,26 @@
   [(P x) (tag-test (T x) fixnum-mask fixnum-tag)]
   [(E x) (nop)])
 
-;(define-primop foo safe
-;  [(V) (K 0)])
 
-;(define-primop fixnum-width safe
-;  [(V) (K 0)] ;(K (fxsll (- (* wordsize 8) fx-shift) fx-shift))]
-;  ;[(E) (nop)]
-;  ;[(P) (K #t)]
-;  )
+(define-primop fixnum-width safe
+  [(V) (K (fxsll (- (* wordsize 8) fx-shift) fx-shift))]
+  [(E) (nop)]
+  [(P) (K #t)])
+
+(define-primop least-fixnum safe
+  [(V) (K (sll (- (expt 2 (- (- (* wordsize 8) fx-shift) 1)))
+               fx-shift))]
+  [(E) (nop)]
+  [(P) (K #t)])
+
+(define-primop greatest-fixnum safe
+  [(V) (K (sll (- (expt 2 (- (- (* wordsize 8) fx-shift) 1)) 1)
+               fx-shift))]
+  [(E) (nop)]
+  [(P) (K #t)])
+
+
+
 
 (define-primop $fxzero? unsafe
   [(P x) (prm '= (T x) (K 0))]
diff --git a/src/todo-r6rs.ss b/src/todo-r6rs.ss
index a9f97b5..4d0d32c 100755
--- a/src/todo-r6rs.ss
+++ b/src/todo-r6rs.ss
@@ -257,6 +257,9 @@
     [bitwise-rotate-bit-field                   D bw]
     ;;;
     [fixnum?                                    C fx]
+    [fixnum-width                               C fx] 
+    [least-fixnum                               C fx] 
+    [greatest-fixnum                            C fx] 
     [fx*                                        C fx]
     [fx*/carry                                  D fx]
     [fx+                                        C fx]