1 files changed, 3 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 915330f..62226b8 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,9 @@ endif
 
 INSTALL	= install
 
-CFLAGS += -Wall -DVERSION="\"$(VERSION)\"" -DBUILD_DATE="\"$(BUILD_DATE)\""
+FEATURE_TEST_MACROS = _GNU_SOURCE
+CFLAGS += -Wall $(addprefix -D, $(FEATURE_TEST_MACROS)) \
+	  -DVERSION="\"$(VERSION)\"" -DBUILD_DATE="\"$(BUILD_DATE)\""
 LDFLAGS +=
 
 TARGETS := exchange