Index: share/mk/bsd.sys.mk
===================================================================
--- share/mk/bsd.sys.mk
+++ share/mk/bsd.sys.mk
@@ -234,6 +234,8 @@
 .if ${MK_WARNS} != "no"
 CFLAGS+=	${CWARNFLAGS:M*} ${CWARNFLAGS.${COMPILER_TYPE}}
 CFLAGS+=	${CWARNFLAGS.${.IMPSRC:T}}
+CXXFLAGS+=	${CXXWARNFLAGS:M*} ${CXXWARNFLAGS.${COMPILER_TYPE}}
+CXXFLAGS+=	${CXXWARNFLAGS.${.IMPSRC:T}}
 .endif
 
 CFLAGS+=	 ${CFLAGS.${COMPILER_TYPE}}