diff --git a/README.md b/README.md
index 74b2ffbd..1968fb26 100644
--- a/README.md
+++ b/README.md
@@ -344,6 +344,7 @@ netmask zzz.zzz.zzz.zzz = Network mask of the switch
 port x name xxx         = Name xxx the port number x
 port z 1g               = Set 1g speed for port z
 igmp on/off             = Turn IGMP on or off
+session xxxx            = Web session timeout in seconds (default 200)
 ```
 [To be continue]
 
diff --git a/cmd_parser.c b/cmd_parser.c
index 5a3a3d60..e6decbeb 100644
--- a/cmd_parser.c
+++ b/cmd_parser.c
@@ -41,6 +41,8 @@ extern __xdata struct flash_region_t flash_region;
 
 extern __xdata char passwd[21];
 
+extern __xdata uint16_t session_timeout;
+
 extern __xdata struct dhcp_state dhcp_state;
 
 __xdata uint8_t vlan_names[VLAN_NAMES_SIZE];
@@ -1593,6 +1595,25 @@ void parse_syslog(void)
 	}
 }
 
+void parse_session(void)
+{
+	if (cmd_words_len >= 2) {
+		/* atoi_short() returns zero for no digits and for a value past
+		 * 65535; a zero-second timeout is not useful either, so both
+		 * tests are needed. */
+		if (!atoi_short(cmd_words_b[1]) || !atoi_results_short) {
+			print_string("Must be 1-65535 s\n");
+			return;
+		}
+		session_timeout = atoi_results_short;
+	}
+	/* Also the confirmation after setting: one message for both. */
+	print_string("Session timeout: ");
+	itoa_short(session_timeout);
+	print_string(" s\n");
+}
+
+
 // Parse command into words
 // cmd_words_len contains the number of words found.
 // cmd_words_b[] contains only start of a word offset.
@@ -1895,6 +1916,8 @@ void cmd_parser(void) __banked
 			}
 		} else if (cmd_compare(0, "ingress")) {
 			parse_ingress();
+		} else if (cmd_compare(0, "session")) {
+			parse_session();
 		}
 		else {
 			print_string("Unknown command\n");
diff --git a/html/app.js b/html/app.js
index 0a50b322..4bcb5c73 100644
--- a/html/app.js
+++ b/html/app.js
@@ -427,6 +427,7 @@ var CONF_CMDS=[
   /^ip\s+(\d{1,3}\.){3}\d{1,3}$/,/^ip\s+dhcp$/,
   /^gw\s+(\d{1,3}\.){3}\d{1,3}$/,/^netmask\s+(\d{1,3}\.){3}\d{1,3}$/,
   /^syslog\s+(on|off)$/,/^syslog\s+ip\s+(\d{1,3}\.){3}\d{1,3}$/,/^syslog\s+port\s+\d{1,5}$/,
+  /^session\s+\d{1,5}$/,
   /^passwd\s+\S+$/,/^hostname\s+\S{1,23}$/,
   /^vlan\s+\d{1,4}\s+d$/,/^vlan\s+\d{1,4}\s+mgmt$/,
   /^vlan\s+\d{1,4}(\s+[a-zA-Z]\w*)?(\s+\d{1,2}t?)+$/,
@@ -1612,7 +1613,7 @@ tabHooks.system={enter:sysLoad};
 
 var CONF_OVERWRITE=[
   /^ip\b/,/^gw\b/,/^netmask\b/,/^hostname\b/,
-  /^syslog\s+ip\b/,/^syslog\s+port\b/,/^passwd\b/,
+  /^syslog\s+ip\b/,/^syslog\s+port\b/,/^passwd\b/,/^session\b/,
   /^vlan\s+\d{1,4}\s+mgmt$/,/^vlan\s+\d{1,4}(?!\s+mgmt\b)/,
   /^pvid\s+\d{1,2}\b/,/^ingress\b/,
   /^port\s+\d{1,2}(?!\s+name\b)/,/^port\s+\d{1,2}\s+name\b/,
diff --git a/httpd/httpd.c b/httpd/httpd.c
index f87de897..41a3fc65 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -12,7 +12,11 @@
 #include "debug.h"
 
 #define SESSION_ID_LENGTH 12
-#define SESSION_TIMEOUT 200
+#define SESSION_TIMEOUT_DEFAULT 200
+
+/* Seconds of inactivity after which a session cookie stops validating.
+ * Configurable with the "session" command, see cmd_parser.c. */
+__xdata uint16_t session_timeout = SESSION_TIMEOUT_DEFAULT;
 
 #define CMARK_S 6
 
@@ -341,7 +345,7 @@ __xdata uint8_t *scan_header(__xdata uint8_t * __xdata p)
 	read_reg_timer(&now);
 
 	if (session) {
-		if (now - last_session_use > SESSION_TIMEOUT) {
+		if (now - last_session_use > session_timeout) {
 			dbg_string("Session expired\n");
 		} else {
 			if (is_word_x(session, session_id)) {