diff --git a/src/clos/streams.lsp b/src/clos/streams.lsp
index 04fc2e575..2722fa224 100644
--- a/src/clos/streams.lsp
+++ b/src/clos/streams.lsp
@@ -602,7 +602,7 @@
     (declare (fixnum end))
     (do ((pos start (1+ pos)))
 	((>= pos end))
-      (declare (type index pos))
+      (declare (type si::index pos))
       (stream-write-char stream (aref string pos))))
   string)