diff --git a/core/sbufs/sbufs.factor b/core/sbufs/sbufs.factor
index 4ed47b20a3..3753be7729 100644
--- a/core/sbufs/sbufs.factor
+++ b/core/sbufs/sbufs.factor
@@ -9,7 +9,7 @@ IN: sbufs
 M: sbuf set-nth-unsafe
     underlying >r >r >fixnum r> >fixnum r> set-char-slot ;
 
-M: sbuf new drop [ 0 <string> ] keep string>sbuf ;
+M: sbuf new drop [ 0 <string> ] keep >fixnum string>sbuf ;
 
 : >sbuf ( seq -- sbuf ) SBUF" " clone-like ; inline