diff --git a/library.scm b/library.scm
index 8fcba9bc..1d480bee 100644
--- a/library.scm
+++ b/library.scm
@@ -3936,7 +3936,7 @@ EOF
 ; 0:  (read-char PORT) -> CHAR | EOF
 ; 1:  (peek-char PORT) -> CHAR | EOF
 ; 2:  (write-char PORT CHAR)
-; 3:  (write-bytevector PORT BYTEVECTOR START END)
+; 3:  (write-bytevector BYTEVECTOR PORT START END)
 ; 4:  (close PORT DIRECTION)
 ; 5:  (flush-output PORT)
 ; 6:  (char-ready? PORT) -> BOOL