--- Libc/Libc-583/threads/Makefile.inc
+++ Libc/Libc-498/threads/Makefile.inc
@@ -1,5 +1,9 @@
 .PATH: ${.CURDIR}/${MACHINE_ARCH}/threads ${.CURDIR}/threads
 
-.sinclude "${.CURDIR}/${MACHINE_ARCH}/threads/Makefile.inc"
+.ifnmake autopatch
+.if exists(${.CURDIR}/${MACHINE_ARCH}/threads/Makefile.inc)
+.include "${.CURDIR}/${MACHINE_ARCH}/threads/Makefile.inc"
+.endif
+.endif # !autopatch
 
 MISRCS += cprocs.c       cthreads.c     lu_utils.c     mig_support.c