diff --git a/apps/telnetd/telnetd.c b/apps/telnetd/telnetd.c
index c168b19b8..37c3fd6cc 100644
--- a/apps/telnetd/telnetd.c
+++ b/apps/telnetd/telnetd.c
@@ -62,6 +62,10 @@ static char telnetd_reject_text[] =
             "Too many connections, please try again later.";
 #endif
 
+#ifndef TELNETD_CONF_MAX_IDLE_TIME
+#define TELNETD_CONF_MAX_IDLE_TIME (CLOCK_SECOND * 30)
+#endif
+
 struct telnetd_state {
   char buf[TELNETD_CONF_LINELEN + 1];
   char bufptr;
@@ -74,7 +78,9 @@ struct telnetd_state {
 #define STATE_DO     4
 #define STATE_DONT   5
 #define STATE_CLOSE  6
+#if TELNETD_CONF_MAX_IDLE_TIME
   struct timer silence_timer;
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
 };
 static struct telnetd_state s;
 
@@ -102,8 +108,6 @@ static struct telnetd_buf buf;
 
 static uint8_t connected;
 
-#define MAX_SILENCE_TIME (CLOCK_SECOND * 30)
-
 /*---------------------------------------------------------------------------*/
 static void
 buf_init(struct telnetd_buf *buf)
@@ -359,7 +363,9 @@ telnetd_appcall(void *ts)
       s.state = STATE_NORMAL;
       connected = 1;
       shell_start();
-      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
+#if TELNETD_CONF_MAX_IDLE_TIME
+      timer_set(&s.silence_timer, TELNETD_CONF_MAX_IDLE_TIME);
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
       ts = (char *)0;
     } else {
       uip_send(telnetd_reject_text, strlen(telnetd_reject_text));
@@ -381,11 +387,15 @@ telnetd_appcall(void *ts)
       connected = 0;
     }
     if(uip_acked()) {
-      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
+#if TELNETD_CONF_MAX_IDLE_TIME
+      timer_set(&s.silence_timer, TELNETD_CONF_MAX_IDLE_TIME);
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
       acked();
     }
     if(uip_newdata()) {
-      timer_set(&s.silence_timer, MAX_SILENCE_TIME);
+#if TELNETD_CONF_MAX_IDLE_TIME
+      timer_set(&s.silence_timer, TELNETD_CONF_MAX_IDLE_TIME);
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
       newdata();
     }
     if(uip_rexmit() ||
@@ -394,16 +404,20 @@ telnetd_appcall(void *ts)
        uip_connected() ||
        uip_poll()) {
       senddata();
+#if TELNETD_CONF_MAX_IDLE_TIME
       if(s.numsent > 0) {
-	timer_set(&s.silence_timer, MAX_SILENCE_TIME);
+	timer_set(&s.silence_timer, TELNETD_CONF_MAX_IDLE_TIME);
       }
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
     }
+#if TELNETD_CONF_MAX_IDLE_TIME
     if(uip_poll()) {
       if(timer_expired(&s.silence_timer)) {
         uip_close();
         tcp_markconn(uip_conn, NULL);
       }
     }
+#endif /* TELNETD_CONF_MAX_IDLE_TIME */
   }
 }
 /*---------------------------------------------------------------------------*/
diff --git a/platform/apple2enh/contiki-conf.h b/platform/apple2enh/contiki-conf.h
index 58316ca6d..2ad5ceb7f 100644
--- a/platform/apple2enh/contiki-conf.h
+++ b/platform/apple2enh/contiki-conf.h
@@ -55,6 +55,10 @@
 #define IRC_CONF_WIDTH  80
 #define IRC_CONF_HEIGHT 23
 
+#ifndef TELNETD_CONF_MAX_IDLE_TIME
+#define TELNETD_CONF_MAX_IDLE_TIME 300
+#endif
+
 #define WWW_CONF_WEBPAGE_HEIGHT 19
 #define WWW_CONF_HISTORY_SIZE    4
 #define WWW_CONF_WGET_EXEC(url) exec("wget", url)
diff --git a/platform/atarixl/contiki-conf.h b/platform/atarixl/contiki-conf.h
index 967112637..8c43fdcae 100644
--- a/platform/atarixl/contiki-conf.h
+++ b/platform/atarixl/contiki-conf.h
@@ -60,6 +60,10 @@
 #define IRC_CONF_WIDTH  40
 #define IRC_CONF_HEIGHT 23
 
+#ifndef TELNETD_CONF_MAX_IDLE_TIME
+#define TELNETD_CONF_MAX_IDLE_TIME 300
+#endif
+
 #define WWW_CONF_WEBPAGE_WIDTH  40
 #define WWW_CONF_WEBPAGE_HEIGHT 19
 #define WWW_CONF_HISTORY_SIZE    4
diff --git a/platform/c128/contiki-conf.h b/platform/c128/contiki-conf.h
index 2bad0a6e6..53a6878f9 100644
--- a/platform/c128/contiki-conf.h
+++ b/platform/c128/contiki-conf.h
@@ -65,6 +65,10 @@
 #define IRC_CONF_WIDTH  80
 #define IRC_CONF_HEIGHT 24
 
+#ifndef TELNETD_CONF_MAX_IDLE_TIME
+#define TELNETD_CONF_MAX_IDLE_TIME 300
+#endif
+
 #define WWW_CONF_HISTORY_SIZE       0
 #define WWW_CONF_FORMS              0
 #define WWW_CONF_PAGEATTRIB_SIZE 1500
diff --git a/platform/c64/contiki-conf.h b/platform/c64/contiki-conf.h
index 868d4dcd1..bfaf1c956 100644
--- a/platform/c64/contiki-conf.h
+++ b/platform/c64/contiki-conf.h
@@ -65,6 +65,10 @@
 #define IRC_CONF_WIDTH  40
 #define IRC_CONF_HEIGHT 24
 
+#ifndef TELNETD_CONF_MAX_IDLE_TIME
+#define TELNETD_CONF_MAX_IDLE_TIME 300
+#endif
+
 #define WWW_CONF_WEBPAGE_WIDTH  40
 #define WWW_CONF_HISTORY_SIZE    4
 #define WWW_CONF_WGET_EXEC(url) exec("wget", url)
diff --git a/platform/win32/contiki-conf.h b/platform/win32/contiki-conf.h
index 81d6b9fcd..060648c36 100644
--- a/platform/win32/contiki-conf.h
+++ b/platform/win32/contiki-conf.h
@@ -171,8 +171,9 @@ typedef unsigned short uip_stats_t;
 #define SHELL_GUI_CONF_YSIZE 30
 
 
+#define TELNETD_CONF_MAX_IDLE_TIME 300
 #ifdef PLATFORM_BUILD
-#define TELNETD_CONF_GUI 1
+#define TELNETD_CONF_GUI             1
 #endif /* PLATFORM_BUILD */