diff --git a/src/Makefile.am b/src/Makefile.am
index 48c861d..ec7250b 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,11 +11,13 @@
 hnbgw_SOURCES = hnbap_encoder.c hnbap_decoder.c rua_encoder.c rua_decoder.c ranap_common.c rua_common.c hnbap_common.c iu_helpers.c asn1helpers.c hnbgw.c hnbgw_hnbap.c hnbgw_rua.c hnbgw_ranap.c ranap_decoder.c ranap_encoder.c ranap_msg_factory.c
 hnbgw_LDADD = $(OSMOCORE_LIBS) $(OSMOVTY_LIBS) $(OSMOGSM_LIBS) $(ASN1C_LIBS) $(COMMON_LDADD) hnbap/libosmo-asn1-hnbap.a rua/libosmo-asn1-rua.a ranap/libosmo-asn1-ranap.a
 
+BUILT_SOURCES = hnbap_decoder.c hnbap_encoder.c rua_decoder.c rua_encoder.c ranap_decoder.c ranap_encoder.c
+
 hnbap_encoder.c hnbap_decoder.c hnbap_ies_defs.h: $(ASN1_ROOT)/hnbap/HNBAP-PDU-Contents.asn
 	$(ASN1TOSTRUCT) -f $<
 
 rua_encoder.c rua_decoder.c rua_ies_defs.h: $(ASN1_ROOT)/rua/RUA-PDU-Contents.asn
 	$(ASN1TOSTRUCT) -p RUA_ -f $<
 
-ranap_encoder.c rua_decoder.c rua_ies_defs.h : $(ASN1_ROOT)/ranap/RANAP-PDU-Contents.asn
+ranap_encoder.c rua_decoder.c rua_ies_defs.h: $(ASN1_ROOT)/ranap/RANAP-PDU-Contents.asn
 	$(ASN1TOSTRUCT) -p RANAP_ -f $<