diff --git a/src/sysdep.c b/src/sysdep.c
index 360e42ba108..28ab676c69c 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -331,8 +331,12 @@ discard_tty_input ()
    the terminal.  */
 
 void
+#ifdef PROTOTYPES
+stuff_char (char c)
+#else
 stuff_char (c)
      char c;
+#endif
 {
   if (read_socket_hook)
     return;