diff --git a/sys/rump/net/lib/libpppoe/Makefile b/sys/rump/net/lib/libpppoe/Makefile
index f6ecfdff9bc9..82040865f118 100644
--- a/sys/rump/net/lib/libpppoe/Makefile
+++ b/sys/rump/net/lib/libpppoe/Makefile
@@ -9,5 +9,9 @@ SRCS=	if_pppoe.c if_spppsubr.c
 
 SRCS+=	pppoe_component.c
 
+.ifdef RUMP_DEBUG
+CPPFLAGS.if_pppoe.c+=	-DPPPOE_DEBUG
+.endif
+
 .include <bsd.lib.mk>
 .include <bsd.klinks.mk>