diff --git a/src/usr/isteps/mss/runtime/makefile b/src/usr/isteps/mss/runtime/makefile
index 530a68f8ded..f3ec739e098 100644
--- a/src/usr/isteps/mss/runtime/makefile
+++ b/src/usr/isteps/mss/runtime/makefile
@@ -5,7 +5,7 @@
 #
 # OpenPOWER HostBoot Project
 #
-# Contributors Listed Below - COPYRIGHT 2019
+# Contributors Listed Below - COPYRIGHT 2019,2020
 # [+] International Business Machines Corp.
 #
 #
@@ -92,7 +92,7 @@ OBJS += memory_size.o
 OBJS += gen_mss_mcbist_patterns.o
 OBJS += axone_pos.o
 OBJS += nimbus_pos.o
-
+OBJS += unmask.o
 
 
 #HWP build tool