diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 295fb86..f406dd7 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -2,7 +2,7 @@
 AM_CFLAGS=-Wall -fno-strict-aliasing $(LIBOSMOCORE_CFLAGS) \
 	$(LIBOSMOGSM_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(LIBOSMOCTRL_CFLAGS) \
 	$(LIBOSMOABIS_CFLAGS) $(LIBOSMOGB_CFLAGS) $(COVERAGE_CFLAGS) \
-	$(LIBCARES_CFLAGS) $(LIBCRYPTO_CFLAGS)
+	$(LIBCARES_CFLAGS) $(LIBCRYPTO_CFLAGS) $(LIBGTP_CFLAGS)
 OSMO_LIBS = $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(LIBOSMOVTY_LIBS) \
 	    $(LIBOSMOCTRL_LIBS) $(LIBOSMOGB_LIBS)