diff --git a/racket/collects/data/private/count-bits-in-fixnum.rkt b/racket/collects/data/private/count-bits-in-fixnum.rkt
index f9b7deb38e..b064ed11af 100644
--- a/racket/collects/data/private/count-bits-in-fixnum.rkt
+++ b/racket/collects/data/private/count-bits-in-fixnum.rkt
@@ -38,7 +38,10 @@
     [(_ expr bits0)
      ;; Choose at compile time what word length is
      (let* ([bits (syntax-e #'bits0)]
-            [bits (or bits (if (fixnum? (expt 2 61)) 62 30))]
+            [bits (or bits 
+                      ;; for portable bytecode, use a fixnum size tha
+                      ;; always works:
+                      30)]
             [lut
              (cond [(<= bits 8) lut8]
                    [(<= bits 30) lut30]