diff --git a/Makefile.inc1 b/Makefile.inc1
index 0a85d6be6be9..ac2bcf7b22b0 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -3260,7 +3260,7 @@ DTBOUTPUTPATH= ${.CURDIR}
 #
 builddtb: .PHONY
 	@PATH=${TMPPATH} MACHINE=${TARGET} \
-	${.CURDIR}/sys/tools/fdt/make_dtb.sh ${.CURDIR}/sys \
+	sh ${.CURDIR}/sys/tools/fdt/make_dtb.sh ${.CURDIR}/sys \
 	    "${FDT_DTS_FILE}" ${DTBOUTPUTPATH}
 
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