diff --git a/src/Makefile.Linux b/src/Makefile.Linux
index ca852f15..d15c968e 100644
--- a/src/Makefile.Linux
+++ b/src/Makefile.Linux
@@ -1,2 +1,2 @@
 LDLIBS_RC += -ldl
-CPPFLAGS += -D_GNU_SOURCE
+CPPFLAGS += -D_BSD_SOURCE -D_XOPEN_SOURCE=500