diff --git a/scheme/vm/prim-io.scm b/scheme/vm/prim-io.scm
index e6bbe59..6c65814 100644
--- a/scheme/vm/prim-io.scm
+++ b/scheme/vm/prim-io.scm
@@ -370,8 +370,8 @@
   (lambda (from from-index to to-index count)
     (cond ((and (or (vm-string? from)
 		    (code-vector? from))
-		(or (vm-string? from)
-		    (code-vector? from))
+		(or (vm-string? to)
+		    (code-vector? to))
 		(<= 0 from-index)
 		(<= 0 to-index)
 		(<= 0 count)