diff --git a/scheme/last-revision b/scheme/last-revision
index ac86b8c..3f04454 100644
--- a/scheme/last-revision
+++ b/scheme/last-revision
@@ -1 +1 @@
-1857
+1858
diff --git a/scheme/pass-specify-rep-primops.ss b/scheme/pass-specify-rep-primops.ss
index f3b278d..1b81245 100644
--- a/scheme/pass-specify-rep-primops.ss
+++ b/scheme/pass-specify-rep-primops.ss
@@ -1596,6 +1596,7 @@
 (define-primop fxarithmetic-shift-right safe
   [(V x n) 
    (struct-case n 
+     ;;; FIXME: check for known types
      [(constant i)
       (cond
         [(and (fx? i)
@@ -1615,7 +1616,7 @@
           (interrupt-when 
             (prm '>= n (K (- (* wordsize 8) fx-shift))))
           (prm 'sll 
-               (prm 'sra x n)
+               (prm 'sra (prm 'sra x n) (K fx-shift))
                (K fx-shift))))])])