diff --git a/appl/ftp/ftp/security.h b/appl/ftp/ftp/security.h
index 19ba4cf6b..102287148 100644
--- a/appl/ftp/ftp/security.h
+++ b/appl/ftp/ftp/security.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 1999 Kungliga Tekniska Högskolan
+ * Copyright (c) 1998 - 2000 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden). 
  * All rights reserved. 
  *
@@ -95,13 +95,17 @@ void delete_ftp_command(void);
 
 int sec_fflush (FILE *);
 int sec_fprintf (FILE *, const char *, ...);
+    __attribute__ ((format (printf, 2,3)));
 int sec_getc (FILE *);
 int sec_putc (int, FILE *);
 int sec_read (int, void *, int);
 int sec_read_msg (char *, int);
 int sec_vfprintf (FILE *, const char *, va_list);
-int sec_fprintf2(FILE *f, const char *fmt, ...);
+    __attribute__ ((format (printf, 2,0)));
+int sec_fprintf2(FILE *f, const char *fmt, ...)
+    __attribute__ ((format (printf, 2,3)));
 int sec_vfprintf2(FILE *, const char *, va_list);
+    __attribute__ ((format (printf, 2,0)));
 int sec_write (int, char *, int);
 
 #ifdef FTP_SERVER