diff --git a/agent/test/Makefile b/agent/test/Makefile
index 26e984a..5897ad3 100644
--- a/agent/test/Makefile
+++ b/agent/test/Makefile
@@ -21,7 +21,7 @@
 TOP_DIR=`pwd`
 OPENOLTDEVICE ?= sim
 
-OPENOLT_PROTO_VER ?= v5.1.0
+OPENOLT_PROTO_VER ?= v5.2.1
 
 ########################################################################
 ##