diff --git a/src/ikarus.boot b/src/ikarus.boot
index a76a120..38e3399 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.numerics.ss b/src/ikarus.numerics.ss
index 5ee3b1e..270aa59 100644
--- a/src/ikarus.numerics.ss
+++ b/src/ikarus.numerics.ss
@@ -188,6 +188,8 @@
             (foreign-call "ikrt_fxbnmult" x y)]
            [(flonum? y)
             ($fl* (fixnum->flonum x) y)]
+           [(ratnum? y) 
+            (binary/ (binary* x ($ratnum-n y)) ($ratnum-d y))]
            [else 
             (error '* "~s is not a number" y)])]
         [(bignum? x)
@@ -198,6 +200,8 @@
             (foreign-call "ikrt_bnbnmult" x y)]
            [(flonum? y)
             ($fl* (bignum->flonum x) y)]
+           [(ratnum? y) 
+            (binary/ (binary* x ($ratnum-n y)) ($ratnum-d y))]
            [else 
             (error '* "~s is not a number" y)])]
         [(flonum? x)
@@ -208,8 +212,15 @@
             ($fl* x (bignum->flonum y))]
            [(flonum? y)
             ($fl* x y)]
+           [(ratnum? y) 
+            (binary/ (binary* x ($ratnum-n y)) ($ratnum-d y))]
            [else
             (error '* "~s is not a number" y)])]
+        [(ratnum? y) 
+         (if (ratnum? x) 
+             (binary/ (binary* ($ratnum-n x) ($ratnum-n y))
+                      (binary* ($ratnum-d x) ($ratnum-d y)))
+             (binary* y x))]
         [else (error '* "~s is not a number" x)])))
 
   (define +
diff --git a/src/libaltcogen.ss b/src/libaltcogen.ss
index c123ae4..617be91 100644
--- a/src/libaltcogen.ss
+++ b/src/libaltcogen.ss
@@ -1808,7 +1808,10 @@
            [(move-byte)
             (let ([s (set-rem d s)])
               (set-for-each (lambda (y) (add-edge! g d y)) s)
-              (for-each (lambda (r) (add-edge! g d r)) non-8bit-registers)
+              (when (var? d)
+                (for-each (lambda (r) (add-edge! g d r)) non-8bit-registers))
+              (when (var? v)
+                (for-each (lambda (r) (add-edge! g v r)) non-8bit-registers))
               (set-union (R v) s))]
            [(int-/overflow int+/overflow int*/overflow)
             (unless (exception-live-set)