diff --git a/src/bacnet/config.h b/src/bacnet/config.h
index 94e1b050..883e2a35 100644
--- a/src/bacnet/config.h
+++ b/src/bacnet/config.h
@@ -171,6 +171,7 @@
 #define BACAPP_SIGNED
 #define BACAPP_REAL
 #define BACAPP_CHARACTER_STRING
+#define BACAPP_BIT_STRING
 #define BACAPP_ENUMERATED
 #define BACAPP_DATE
 #define BACAPP_TIME