diff --git a/Makefile.libcompat b/Makefile.libcompat
index 560a50c4257..2cbaf2e0f19 100644
--- a/Makefile.libcompat
+++ b/Makefile.libcompat
@@ -94,6 +94,7 @@ LIBCOMPATWMAKEENV+=	BUILD_TOOLS_META=.NOMETA_CMP
 .endif
 LIBCOMPATWMAKEFLAGS+= CC="${XCC} ${LIBCOMPATCFLAGS}" \
 		CXX="${XCXX} ${LIBCOMPATCFLAGS} ${LIBCOMPATCXXFLAGS}" \
+		CPP="${XCPP} ${LIBCOMPATCFLAGS}" \
 		DESTDIR=${LIBCOMPATTMP} \
 		-DNO_CPU_CFLAGS \
 		MK_CTF=no \