diff --git a/targets/RT/USER/Makefile b/targets/RT/USER/Makefile
index 17e59c6513..e7826ac425 100644
--- a/targets/RT/USER/Makefile
+++ b/targets/RT/USER/Makefile
@@ -34,6 +34,10 @@ ifdef DEBUG
 CFLAGS += -g -ggdb
 endif
 SRC = synctest.c condtest.c #lte-softmodem.c
+
+ifdef LIBCONFIG_LONG
+CFLAGS += -DLIBCONFIG_LONG
+endif
 
 
 ifndef RTAI