diff --git a/openbsc/src/libmsc/Makefile.am b/openbsc/src/libmsc/Makefile.am
index c29d521..89fee91 100644
--- a/openbsc/src/libmsc/Makefile.am
+++ b/openbsc/src/libmsc/Makefile.am
@@ -16,6 +16,8 @@
 			ussd.c \
 			vty_interface_layer3.c \
 			transaction.c \
-			smpp_smsc.c smpp_openbsc.c \
 			osmo_msc.c
 
+if BUILD_SMPP
+libmsc_a_SOURCES += smpp_smsc.c smpp_openbsc.c
+endif