--- a/mod_muc_markers/mod_muc_markers.lua	Sun Jan 17 21:52:36 2021 +0100
+++ b/mod_muc_markers/mod_muc_markers.lua	Mon Jan 18 20:01:17 2021 +0100
@@ -21,7 +21,7 @@
 end
 
 local marker_element_name = module:get_option_string("muc_marker_type", "displayed");
-local marker_summary_on_join = module:get_option_string("muc_marker_summary_on_join", true);
+local marker_summary_on_join = module:get_option_boolean("muc_marker_summary_on_join", true);
 local rewrite_id_attribute = module:get_option_boolean("muc_marker_rewrite_id", false);
 
 assert(marker_order[marker_element_name], "invalid marker name: "..marker_element_name);