diff --git a/lib/libproc/Makefile b/lib/libproc/Makefile
index f9e01ab..15b27d8 100644
--- a/lib/libproc/Makefile
+++ b/lib/libproc/Makefile
@@ -15,7 +15,10 @@ INCS=	libproc.h
 
 CFLAGS+=	-I${.CURDIR}
 
-.if ${MK_LIBCPLUSPLUS} != "no"
+.if ${CXX:T:M*-stdlib=libc++*}
+LDADD+=		-lcxxrt
+DPADD+=		${LIBCXXRT}
+.elif ${CXXFLAGS:T:M*-stdlib=libc++*}
 LDADD+=		-lcxxrt
 DPADD+=		${LIBCXXRT}
 .else