diff --git a/acls.c b/acls.c
index 0f98df2..5f26d70 100644
--- a/acls.c
+++ b/acls.c
@@ -178,7 +178,7 @@ struct acluser **up;
 #endif
   (*up)->u_Esc = DefaultEsc;
   (*up)->u_MetaEsc = DefaultMetaEsc;
-  strncpy((*up)->u_name, name, 20);
+  strncpy((*up)->u_name, name, MAXSTR);
   (*up)->u_password = NULL;
   if (pass)
     (*up)->u_password = SaveStr(pass);
@@ -314,8 +314,8 @@ struct acluser **up;
     return UserAdd(name, pass, up);
   if (!strcmp(name, "nobody"))		/* he remains without password */
     return -1;
-  strncpy((*up)->u_password, pass ? pass : "", 20);
-  (*up)->u_password[20] = '\0';
+  strncpy((*up)->u_password, pass ? pass : "", MAXSTR);
+  (*up)->u_password[MAXSTR] = '\0';
   return 0;
 }
 #endif
diff --git a/acls.h b/acls.h
index c41b714..7f20f55 100644
--- a/acls.h
+++ b/acls.h
@@ -36,6 +36,16 @@
 #define ACLBYTE(data, w)   ((data)[(w) >> 3])
 #define ACLBIT(w)   (0x80 >> ((w) & 7))
 
+#include <limits.h>
+
+#ifndef NAME_MAX
+# ifndef MAXNAMELEN
+#  define NAME_MAX 255
+# else
+#  define NAME_MAX MAXNAMELEN
+# endif
+#endif
+
 typedef unsigned char * AclBits;
 
 /*
@@ -73,7 +83,7 @@ struct plop
 typedef struct acluser
 {
   struct acluser *u_next;		/* continue the main user list */
-  char u_name[20+1];		/* login name how he showed up */
+  char u_name[NAME_MAX+1];		/* login name how he showed up */
   char *u_password;		/* his password (may be NullStr). */
   int  u_checkpassword;		/* nonzero if this u_password is valid */
   int  u_detachwin;		/* the window where he last detached */
diff --git a/display.h b/display.h
index ef99954..563fcd0 100644
--- a/display.h
+++ b/display.h
@@ -22,6 +22,16 @@
  * $Id: display.h,v 1.9 1994/05/31 12:31:54 mlschroe Exp $ FAU
  */
 
+#include <limits.h>
+
+#ifndef NAME_MAX
+# ifndef MAXNAMELEN
+#  define NAME_MAX 255
+# else
+#  define NAME_MAX MAXNAMELEN
+# endif
+#endif
+
 #ifdef MAPKEYS
 
 #define KMAP_KEYS (T_OCAPS-T_CAPS)
@@ -85,7 +95,7 @@ struct display
   struct win *d_other;		/* pointer to other window */
   int   d_nonblock;		/* -1 don't block if obufmax reached */
 				/* >0: block after nonblock secs */
-  char  d_termname[20 + 1];	/* $TERM */
+  char  d_termname[NAME_MAX + 1]; /* $TERM */
   char	*d_tentry;		/* buffer for tgetstr */
   char	d_tcinited;		/* termcap inited flag */
   int	d_width, d_height;	/* width/height of the screen */
diff --git a/screen.c b/screen.c
index 70741df..6f45b60 100644
--- a/screen.c
+++ b/screen.c
@@ -106,6 +106,16 @@ FILE *dfp;
 #endif
 
 
+#include <limits.h>
+
+#ifndef NAME_MAX
+# ifndef MAXNAMELEN
+#  define NAME_MAX 255
+# else
+#  define NAME_MAX MAXNAMELEN
+# endif
+#endif
+
 extern char Term[], screenterm[], **environ, Termcap[];
 int force_vt = 1;
 int VBellWait, MsgWait, MsgMinWait, SilenceWait;
@@ -877,13 +887,13 @@ char **av;
 
   if (home == 0 || *home == '\0')
     home = ppp->pw_dir;
-  if (strlen(LoginName) > 20)
+  if (strlen(LoginName) > NAME_MAX)
     Panic(0, "LoginName too long - sorry.");
 #ifdef MULTIUSER
-  if (multi && strlen(multi) > 20)
+  if (multi && strlen(multi) > NAME_MAX)
     Panic(0, "Screen owner name too long - sorry.");
 #endif
-  if (strlen(home) > MAXPATHLEN - 25)
+  if (strlen(home) > MAXPATHLEN - NAME_MAX)
     Panic(0, "$HOME too long - sorry.");
 
   attach_tty = "";
diff --git a/screen.h b/screen.h
index 4f9f354..bcaaaf6 100644
--- a/screen.h
+++ b/screen.h
@@ -43,6 +43,15 @@
 #include "comm.h"
 #include "layer.h"
 #include "term.h"
+#include <limits.h>
+
+#ifndef NAME_MAX
+# ifndef MAXNAMELEN
+#  define NAME_MAX 255
+# else
+#  define NAME_MAX MAXNAMELEN
+# endif
+#endif
 
 
 #ifdef DEBUG
@@ -195,26 +204,26 @@ struct msg
       create;
       struct
 	{
-	  char auser[20 + 1];	/* username */
+	  char auser[NAME_MAX + 1];	/* username */
 	  int apid;		/* pid of frontend */
 	  int adaptflag;	/* adapt window size? */
 	  int lines, columns;	/* display size */
 	  char preselect[20];
 	  int esc;		/* his new escape character unless -1 */
 	  int meta_esc;		/* his new meta esc character unless -1 */
-	  char envterm[20 + 1];	/* terminal type */
+	  char envterm[NAME_MAX + 1];	/* terminal type */
 	  int encoding;		/* encoding of display */
 	}
       attach;
       struct 
 	{
-	  char duser[20 + 1];	/* username */
+	  char duser[NAME_MAX + 1];	/* username */
 	  int dpid;		/* pid of frontend */
 	}
       detach;
       struct 
 	{
-	  char auser[20 + 1];	/* username */
+	  char auser[NAME_MAX + 1];	/* username */
 	  int nargs;
 	  char cmd[MAXPATHLEN];	/* command */
 	  int apid;		/* pid of frontend */
diff --git a/socket.c b/socket.c
index 62a73af..1cc9c27 100644
--- a/socket.c
+++ b/socket.c
@@ -45,6 +45,16 @@
 
 #include "extern.h"
 
+#include <limits.h>
+
+#ifndef NAME_MAX
+# ifndef MAXNAMELEN
+#  define NAME_MAX 255
+# else
+#  define NAME_MAX MAXNAMELEN
+# endif
+#endif
+
 static int   CheckPid __P((int));
 static void  ExecCreate __P((struct msg *));
 static void  DoCommandMsg __P((struct msg *));
@@ -1248,7 +1258,7 @@ static void PasswordProcessInput __P((char *, int));
 
 struct pwdata {
   int l;
-  char buf[20 + 1];
+  char buf[NAME_MAX + 1];
   struct msg m;
 };