diff --git a/src/plugin.h b/src/plugin.h
index 0f1307a..fbfed2e 100644
--- a/src/plugin.h
+++ b/src/plugin.h
@@ -38,6 +38,7 @@ typedef void     (*PluginInit)          (server *srv, plugin *p);
 typedef void     (*PluginFree)          (server *srv, plugin *p);
 typedef gboolean (*PluginParseOption)   (server *srv, plugin *p, size_t ndx, option *opt, gpointer *value);
 typedef void     (*PluginFreeOption)    (server *srv, plugin *p, size_t ndx, gpointer value);
+typedef gpointer (*PluginDefaultValue) (server *srv, plugin *p, gsize ndx);
 typedef action*  (*PluginCreateAction)  (server *srv, plugin *p, option *opt);
 typedef gboolean (*PluginSetup)         (server *srv, plugin *p, option *opt);
 
@@ -75,8 +76,8 @@ struct plugin {
 struct plugin_option {
 	const gchar *name;
 	option_type type;
-	gpointer default_value;
 
+	PluginDefaultValue default_value;
 	PluginParseOption parse_option;
 	PluginFreeOption free_option;
 };
@@ -101,12 +102,12 @@ struct server_option {
 	  *
 	  * Default behaviour (NULL) is to just use the option as value
 	  */
+	PluginDefaultValue default_value; /* default value callback - if no callback is provided, default value will be NULL, 0 or FALSE */
 	PluginParseOption parse_option;
 	PluginFreeOption free_option;
 
 	size_t index, module_index;
 	option_type type;
-	gpointer default_value;
 };
 
 struct server_action {
diff --git a/src/plugin_core.c b/src/plugin_core.c
index 8d1bdd5..165827c 100644
--- a/src/plugin_core.c
+++ b/src/plugin_core.c
@@ -424,7 +424,23 @@ void core_option_log_level_free(server *srv, plugin *p, size_t ndx, gpointer val
 	UNUSED(value);
 }
 
-static plugin_option options[] = {
+gpointer core_option_max_keep_alive_idle_default(server *srv, plugin *p, gsize ndx) {
+	UNUSED(srv);
+	UNUSED(p);
+	UNUSED(ndx);
+
+	return GINT_TO_POINTER(5);
+}
+
+gpointer core_option_server_tag_default(server *srv, plugin *p, gsize ndx) {
+	UNUSED(srv);
+	UNUSED(p);
+	UNUSED(ndx);
+
+	return g_string_new_len(CONST_STR_LEN("lighttpd-2.0~sandbox"));
+}
+
+static const plugin_option options[] = {
 	{ "debug.log_request_handling", OPTION_BOOLEAN, NULL, NULL, NULL },
 
 	{ "log.target", OPTION_STRING, NULL, core_option_log_target_parse, core_option_log_target_free },
@@ -432,8 +448,8 @@ static plugin_option options[] = {
 
 	{ "static-file.exclude", OPTION_LIST, NULL, NULL, NULL },
 
-	{ "server.tag", OPTION_STRING, NULL, NULL, NULL },
-	{ "server.max_keep_alive_idle", OPTION_INT, GINT_TO_POINTER(5), NULL, NULL },
+	{ "server.tag", OPTION_STRING, core_option_server_tag_default, NULL, NULL },
+	{ "server.max_keep_alive_idle", OPTION_INT, core_option_max_keep_alive_idle_default, NULL, NULL },
 	{ NULL, 0, NULL, NULL, NULL }
 };
 
@@ -458,10 +474,6 @@ static const plugin_setup setups[] = {
 void plugin_core_init(server *srv, plugin *p) {
 	UNUSED(srv);
 
-	/* default values - if not initialized here, will default to NULL, 0 or FALSE */
-	options[CORE_OPTION_DEBUG_REQUEST_HANDLING].default_value = FALSE;
-	options[CORE_OPTION_SERVER_TAG].default_value = g_string_new_len(CONST_STR_LEN("lighttpd-2.0~sandbox"));
-
 	p->options = options;
 	p->actions = actions;
 	p->setups = setups;
diff --git a/src/server.c b/src/server.c
index cc08857..2e82dd7 100644
--- a/src/server.c
+++ b/src/server.c
@@ -354,7 +354,8 @@ void server_start(server *srv) {
 	g_hash_table_iter_init(&iter, srv->options);
 	while (g_hash_table_iter_next(&iter, &k, &v)) {
 		server_option *so = v;
-		srv->option_def_values[so->index] = so->default_value;
+		if (so->default_value)
+			srv->option_def_values[so->index] = so->default_value(srv, so->p, so->index);
 	}
 
 	plugins_prepare_callbacks(srv);