diff --git a/usr.bin/dtc/Makefile b/usr.bin/dtc/Makefile
--- a/usr.bin/dtc/Makefile
+++ b/usr.bin/dtc/Makefile
@@ -6,6 +6,8 @@
 
 CXXFLAGS+=	-fno-rtti -fno-exceptions
 
+CXXSTD=	c++17
+
 NO_SHARED?=NO
 
 .include <bsd.prog.mk>