diff --git a/plugins/mod_csi_simple.lua b/plugins/mod_csi_simple.lua
index 39b05b070..fdd1fd6ca 100644
--- a/plugins/mod_csi_simple.lua
+++ b/plugins/mod_csi_simple.lua
@@ -161,6 +161,10 @@ function enable_optimizations(session)
 		session.conn:pause_writes();
 		session.csi_measure_buffer_hold = measure_buffer_hold();
 		session.csi_counter = 0;
+		if session.csi_resume then
+			timer.stop(session.csi_resume);
+			session.csi_resume = nil;
+		end
 		filters.add_filter(session, "stanzas/out", manage_buffer);
 		filters.add_filter(session, "bytes/in", flush_buffer);
 	else