diff --git a/rebar.config b/rebar.config
index 268b2aa6b..1c1275542 100644
--- a/rebar.config
+++ b/rebar.config
@@ -441,7 +441,8 @@
 			{d, 'STUB_RANDOMX', true},
 			{d, 'VDF_DIFFICULTY', 2},
 			{d, 'INITIAL_VDF_DIFFICULTY', 2},
-			{d, 'REPLICA_2_9_PACKING_DIFFICULTY', 2}
+			{d, 'REPLICA_2_9_PACKING_DIFFICULTY', 2},
+			{d, 'BLOCK_2_9_SYNCING', true}
 		]}
 	]},
 	{e2e, [