diff --git a/bacnet-stack/ports/at91sam7s/makefile b/bacnet-stack/ports/at91sam7s/makefile
index 9eb7033c..8e82b4b9 100644
--- a/bacnet-stack/ports/at91sam7s/makefile
+++ b/bacnet-stack/ports/at91sam7s/makefile
@@ -16,6 +16,7 @@ BACNET_FLAGS = -DBACDL_MSTP
 BACNET_FLAGS += -DMAX_TSM_TRANSACTIONS=0
 BACNET_FLAGS += -DPRINT_ENABLED=0
 BACNET_FLAGS += -DMAX_APDU=480
+BACNET_FLAGS += -DCRC_USE_TABLE
 #BACNET_FLAGS += -DDLMSTP_TEST
 
 BACNET_ROOT = ../..