diff --git a/src/ikarus.boot b/src/ikarus.boot
index 0ecb681..b1ba670 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/pass-specify-rep-primops.ss b/src/pass-specify-rep-primops.ss
index 58badf4..2359371 100644
--- a/src/pass-specify-rep-primops.ss
+++ b/src/pass-specify-rep-primops.ss
@@ -641,11 +641,18 @@
    (record-case i
      [(constant i) 
       (unless (fixnum? i) (interrupt))
-      (prm 'logand (prm 'sra (T x) (K i)) (K (* -1 fixnum-scale)))]
+      (prm 'logand 
+           (prm 'sra (T x) (K (if (> i 31) 31 i)))
+           (K (* -1 fixnum-scale)))]
      [else 
-      (prm 'logand
-           (prm 'sra (T x) (prm 'sra (T i) (K fixnum-shift)))
-           (K (* -1 fixnum-scale)))])]
+      (with-tmp ([i (prm 'sra (T i) (K fixnum-shift))])
+        (with-tmp ([i (make-conditional
+                        (prm '< i (K 32))
+                        i
+                        (K 31))])
+           (prm 'logand
+                (prm 'sra (T x) i)
+                (K (* -1 fixnum-scale)))))])]
   [(P x i) (K #t)]
   [(E x i) (nop)])
 
diff --git a/src/todo-r6rs.ss b/src/todo-r6rs.ss
index ea4229e..5510012 100755
--- a/src/todo-r6rs.ss
+++ b/src/todo-r6rs.ss
@@ -288,7 +288,7 @@
     [fxmax                                      S fx]
     [fxmin                                      S fx]
     [fxmod                                      D fx]
-    [fxmod0                                     S fx]
+    [fxmod0                                     D fx]
     [fxnegative?                                C fx]
     [fxnot                                      C fx]
     [fxodd?                                     C fx]