diff --git a/tests/sgsn/Makefile.am b/tests/sgsn/Makefile.am
index 802811d..8692fc3 100644
--- a/tests/sgsn/Makefile.am
+++ b/tests/sgsn/Makefile.am
@@ -10,6 +10,7 @@
 	$(LIBOSMOABIS_CFLAGS) \
 	$(LIBOSMOGSM_CFLAGS) \
 	$(LIBCARES_CFLAGS) \
+	$(LIBGTP_CFLAGS) \
 	$(NULL)
 if BUILD_IU
 AM_CFLAGS += \