--- a/wvrules.mk
+++ b/wvrules.mk
@@ -83,7 +83,7 @@
 
 INCFLAGS=$(addprefix -I,$(WVSTREAMS_INC) $(XPATH))
 CPPFLAGS+=$(INCFLAGS) \
-	-D_BSD_SOURCE -D_GNU_SOURCE $(OSDEFINE) \
+	-D_DEFAULT_SOURCE $(OSDEFINE) \
 	-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 \
 	-DUNSTABLE