diff --git a/config.mk b/config.mk
index b7a902f..e49fa24 100644
--- a/config.mk
+++ b/config.mk
@@ -18,7 +18,7 @@ INCS = -I. -I/usr/include -I${X11INC} ${GTKINC}
 LIBS = -L/usr/lib -lc -L${X11LIB} -lX11 ${GTKLIB} -lgthread-2.0
 
 # flags
-CPPFLAGS = -DVERSION=\"${VERSION}\" -D_BSD_SOURCE
+CPPFLAGS = -DVERSION=\"${VERSION}\" -D_DEFAULT_SOURCE
 CFLAGS = -std=c99 -pedantic -Wall -Os ${INCS} ${CPPFLAGS}
 LDFLAGS = -g ${LIBS}