--- a/plugins/mod_csi_simple.lua	Sat Nov 20 19:23:08 2021 +0100
+++ b/plugins/mod_csi_simple.lua	Sat Nov 20 22:50:51 2021 +0100
@@ -143,7 +143,7 @@
 
 local function flush_buffer(data, session)
 	local ctr = session.csi_counter or 0;
-	if ctr == 0 then return data end
+	if ctr == 0 or session.state == "flushing" then return data end
 	session.log("debug", "Flushing buffer (%s; queue size is %d)", "client activity", session.csi_counter);
 	session.state = "flushing";
 	module:fire_event("csi-flushing", { session = session });