diff --git a/agent/test/Makefile b/agent/test/Makefile
index f152e16..ede65a5 100644
--- a/agent/test/Makefile
+++ b/agent/test/Makefile
@@ -21,7 +21,7 @@
 TOP_DIR=`pwd`
 OPENOLTDEVICE ?= sim
 
-OPENOLT_PROTO_VER ?= v5.6.5
+OPENOLT_PROTO_VER ?= v5.6.6
 
 ########################################################################
 ##