diff --git a/src/Makefile.am b/src/Makefile.am
index a3332578f..979df1a58 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -5,7 +5,7 @@
 DIST_SUBDIRS = secp256k1 univalue
 
 AM_LDFLAGS = $(PTHREAD_CFLAGS) $(LIBTOOL_LDFLAGS) $(SAN_LDFLAGS) $(HARDENED_LDFLAGS)
-AM_CXXFLAGS = $(SAN_CXXFLAGS) $(HARDENED_CXXFLAGS) $(ERROR_CXXFLAGS)
+AM_CXXFLAGS = $(SAN_CXXFLAGS) $(HARDENED_CXXFLAGS) $(ERROR_CXXFLAGS) -std=c++17
 AM_CPPFLAGS = $(HARDENED_CPPFLAGS)
 EXTRA_LIBRARIES =
 
diff --git a/util/build.sh b/util/build.sh
index da5622706..7b9bb25ec 100755
--- a/util/build.sh
+++ b/util/build.sh
@@ -154,5 +154,4 @@ fi
 
 cd $WD
 
-CXXFLAGS+=-std=gnu17
 time "$MAKE" "$@" V=1