diff --git a/Makefile.inc1 b/Makefile.inc1
index 59b6629910f6..149ab658be81 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -1458,8 +1458,8 @@ _xi-links:
 DTBOUTPUTPATH= ${KRNLOBJDIR}/${KERNCONF}/
 
 .if !defined(FDT_DTS_FILE) || empty(FDT_DTS_FILE)
-FDT_DTS_FILE!=	 grep "^makeoptions[[:space:]]\+FDT_DTS_FILE" \
-	${KERNCONFDIR}/${KERNCONF} 2> /dev/null | cut -d= -f2
+FDT_DTS_FILE!= awk '/^makeoptions[[:space:]]+FDT_DTS_FILE/ {FS="=|[ \t]+"; print $$3}' \
+	${KERNCONFDIR}/${KERNCONF}
 .endif
 
 .endif