diff --git a/resources/prosody-plugins/mod_jitsi_session.lua b/resources/prosody-plugins/mod_jitsi_session.lua
index 4ae56e73e4..01619c16ba 100644
--- a/resources/prosody-plugins/mod_jitsi_session.lua
+++ b/resources/prosody-plugins/mod_jitsi_session.lua
@@ -20,7 +20,7 @@ function init_session(event)
 
         -- The room name and optional prefix from the web query
         session.jitsi_web_query_room = urlencode(params.room);
-        session.jitsi_web_query_prefix = params.prefix or "";
+        session.jitsi_web_query_prefix = urlencode(params.prefix) or "";
     end
 end