diff --git a/acsApp/src/Makefile b/acsApp/src/Makefile
index 5433d77..7b97758 100644
--- a/acsApp/src/Makefile
+++ b/acsApp/src/Makefile
@@ -13,6 +13,7 @@ SRCS += AcsRegister.cc
 
 # Advanced Control Systems driver support.
 SRCS += devMCB4B.c drvMCB4B.c
+SRCS += MCB4BDriver.cpp
 
 Acs_LIBS += motor asyn
 Acs_LIBS += $(EPICS_BASE_IOC_LIBS)