diff --git a/rosette/base/primitive.rkt b/rosette/base/primitive.rkt
index 1540dd68..89850739 100644
--- a/rosette/base/primitive.rkt
+++ b/rosette/base/primitive.rkt
@@ -131,4 +131,4 @@
       (begin
         (assert (>= start 0))
         (assert (>= end start))
-        (bitwise-and (sub1 (<< 1 (- end start))) (>> n start)))))
\ No newline at end of file
+        (bitwise-and (@sub1 (<< 1 (- end start))) (>> n start)))))