diff --git a/src/ikarus.boot b/src/ikarus.boot
index 8cba868..dc981a2 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/ikarus.intel-assembler.ss b/src/ikarus.intel-assembler.ss
index 1e51a49..17e7591 100644
--- a/src/ikarus.intel-assembler.ss
+++ b/src/ikarus.intel-assembler.ss
@@ -478,6 +478,13 @@
       [(and (xmmreg? src) (or (xmmreg? dst) (mem? dst)))
        (CODE #xF2 (CODE #x0F ((CODE/digit #x11 src) dst ac)))]
       [else (error who "invalid ~s" instr)])]
+   [(cvtsi2sd src dst)
+    (cond
+      [(and (xmmreg? dst) (reg? src))
+       (CODE #xF2 (CODE #x0F (CODE #x2A (ModRM 3 src dst ac))))]
+      [(and (xmmreg? dst) (mem? src))
+       (CODE #xF2 (CODE #x0F ((CODE/digit #x2A dst) src ac)))]
+      [else (error who "invalid ~s" instr)])] 
    [(addsd src dst)
     (cond
       [(and (xmmreg? dst) (or (xmmreg? src) (mem? src)))
diff --git a/src/ikarus.numerics.ss b/src/ikarus.numerics.ss
index a2ef270..ce646cc 100644
--- a/src/ikarus.numerics.ss
+++ b/src/ikarus.numerics.ss
@@ -152,8 +152,7 @@
             sin cos atan sqrt
             flround flmax))
 
-  (define (fixnum->flonum x)
-    (foreign-call "ikrt_fixnum_to_flonum" x))
+;    (foreign-call "ikrt_fixnum_to_flonum" x))
 
   (module (bignum->flonum)
     ;  sbe         f6     f5       f4       f3       f2       f1       f0
@@ -362,7 +361,7 @@
            [(bignum? y)
             (foreign-call "ikrt_fxbnplus" x y)]
            [(flonum? y)
-            ($fl+ (fixnum->flonum x) y)]
+            ($fl+ ($fixnum->flonum x) y)]
            [(ratnum? y)
             ($make-ratnum
               (+ (* x ($ratnum-d y)) ($ratnum-n y))
@@ -386,7 +385,7 @@
         [(flonum? x)
          (cond
            [(fixnum? y)
-            ($fl+ x (fixnum->flonum y))]
+            ($fl+ x ($fixnum->flonum y))]
            [(bignum? y)
             ($fl+ x (bignum->flonum y))]
            [(flonum? y)
@@ -445,7 +444,7 @@
            [(flonum? y)
             (if ($fx= x 0)
                 ($fl* y -1.0)
-                ($fl- (fixnum->flonum x) y))]
+                ($fl- ($fixnum->flonum x) y))]
            [(ratnum? y) 
             (let ([n ($ratnum-n y)] [d ($ratnum-d y)])
               (binary/ (binary- (binary* d x) n) d))]
@@ -467,7 +466,7 @@
         [(flonum? x)
          (cond
            [(fixnum? y)
-            ($fl- x (fixnum->flonum y))]
+            ($fl- x ($fixnum->flonum y))]
            [(bignum? y)
             ($fl- x (bignum->flonum y))]
            [(flonum? y)
@@ -500,7 +499,7 @@
            [(bignum? y)
             (foreign-call "ikrt_fxbnmult" x y)]
            [(flonum? y)
-            ($fl* (fixnum->flonum x) y)]
+            ($fl* ($fixnum->flonum x) y)]
            [(ratnum? y) 
             (binary/ (binary* x ($ratnum-n y)) ($ratnum-d y))]
            [else 
@@ -520,7 +519,7 @@
         [(flonum? x)
          (cond
            [(fixnum? y)
-            ($fl* x (fixnum->flonum y))]
+            ($fl* x ($fixnum->flonum y))]
            [(bignum? y)
             ($fl* x (bignum->flonum y))]
            [(flonum? y)
@@ -684,13 +683,13 @@
         [(flonum? x)
          (cond
            [(flonum? y) ($fl/ x y)]
-           [(fixnum? y) ($fl/ x (fixnum->flonum y))]
+           [(fixnum? y) ($fl/ x ($fixnum->flonum y))]
            [(bignum? y) ($fl/ x (bignum->flonum y))]
            [(ratnum? y) ($fl/ x (ratnum->flonum y))]
            [else (error '/ "unspported ~s ~s" x y)])]
         [(fixnum? x)
          (cond
-           [(flonum? y) ($fl/ (fixnum->flonum x) y)]
+           [(flonum? y) ($fl/ ($fixnum->flonum x) y)]
            [(fixnum? y)
             (cond
               [($fx= y 0) (error '/ "division by 0")]
@@ -936,7 +935,7 @@
   (define exact->inexact
     (lambda (x)
       (cond
-        [(fixnum? x) (fixnum->flonum x)]
+        [(fixnum? x) ($fixnum->flonum x)]
         [(bignum? x) (bignum->flonum x)]
         [(ratnum? x) 
          (binary/ (exact->inexact ($ratnum-n x)) ($ratnum-d x))]
@@ -1201,11 +1200,11 @@
          (define-syntax flfl? 
            (syntax-rules () [(_ x y) (fl? x y)]))
          (define-syntax flfx? 
-           (syntax-rules () [(_ x y) (fl? x (fixnum->flonum y))]))
+           (syntax-rules () [(_ x y) (fl? x ($fixnum->flonum y))]))
          (define-syntax flbn? 
            (syntax-rules () [(_ x y) (fl? x (bignum->flonum y))]))
          (define-syntax fxfl? 
-           (syntax-rules () [(_ x y) (fl? (fixnum->flonum x) y)]))
+           (syntax-rules () [(_ x y) (fl? ($fixnum->flonum x) y)]))
          (define-syntax bnfl? 
            (syntax-rules () [(_ x y) (fl? (bignum->flonum x) y)])))]))
 
diff --git a/src/libaltcogen.ss b/src/libaltcogen.ss
index acf20e4..395b3b8 100644
--- a/src/libaltcogen.ss
+++ b/src/libaltcogen.ss
@@ -443,7 +443,8 @@
                 (make-asm-instr op
                   (make-disp (car s*) (cadr s*)) 
                   (caddr s*))))]
-         [(fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!) 
+         [(fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!
+                   fl:from-int) 
           (S* rands
               (lambda (s*)
                 (make-asm-instr op (car s*) (cadr s*))))]
@@ -1398,7 +1399,7 @@
           (mark-reg/vars-conf! edx vs)
           (R s vs (rem-reg edx rs) fs ns)]
          [(mset bset/c bset/h fl:load fl:store fl:add! fl:sub!
-                fl:mul! fl:div!) 
+                fl:mul! fl:div! fl:from-int) 
           (R* (list s d) vs rs fs ns)]
          [else (error who "invalid effect op ~s" (unparse x))])]
       [(ntcall target value args mask size)
@@ -1602,7 +1603,8 @@
            [(logand logor logxor int+ int- int* mset bset/c bset/h 
               sll sra srl
               cltd idiv int-/overflow int+/overflow int*/overflow
-              fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!)
+              fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!
+              fl:from-int)
             (make-asm-instr op (R d) (R s))]
            [(nop) (make-primcall 'nop '())]
            [else (error who "invalid op ~s" op)])]
@@ -1848,7 +1850,8 @@
                   s))
               (set-union (set-union (R eax) (R edx))
                      (set-union (R v) s)))]
-           [(mset fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!)
+           [(mset fl:load fl:store fl:add! fl:sub! fl:mul! fl:div!
+                  fl:from-int)
             (set-union (R v) (set-union (R d) s))]
            [else (error who "invalid effect ~s" x)])]
         [(seq e0 e1) (E e0 (E e1 s))]
@@ -2180,6 +2183,7 @@
                    (E (make-asm-instr 'move u a))
                    (E (make-asm-instr op u b))))]
               [else x])]
+           [(fl:from-int) x]
            [else (error who "invalid effect ~s" op)])]
         [(primcall op rands) 
          (case op
@@ -2461,6 +2465,8 @@
           (cons `(movsd xmm0 ,(R (make-disp s d))) ac)]
          [(fl:load) 
           (cons `(movsd ,(R (make-disp s d)) xmm0) ac)]
+         [(fl:from-int) 
+          (cons `(cvtsi2sd ,(R s) xmm0) ac)]
          [(fl:add!) 
           (cons `(addsd ,(R (make-disp s d)) xmm0) ac)]
          [(fl:sub!) 
diff --git a/src/pass-specify-rep-primops.ss b/src/pass-specify-rep-primops.ss
index d836664..040984b 100644
--- a/src/pass-specify-rep-primops.ss
+++ b/src/pass-specify-rep-primops.ss
@@ -777,7 +777,9 @@
   [(V fx) 
    (with-tmp ([x (prm 'alloc (K (align flonum-size)) (K vector-tag))])
      (prm 'mset x (K (- vector-tag)) (K flonum-tag))
-     (prm 'fl:from-int (prm 'sll (T fx) (K fx-shift)))
+     (prm 'fl:from-int
+          (K 0) ; dummy
+          (prm 'sra (T fx) (K fx-shift)))
      (prm 'fl:store x (K (- disp-flonum-data vector-tag)))
      x)])