diff --git a/usr.sbin/freebsd-update/freebsd-update.sh b/usr.sbin/freebsd-update/freebsd-update.sh
--- a/usr.sbin/freebsd-update/freebsd-update.sh
+++ b/usr.sbin/freebsd-update/freebsd-update.sh
@@ -2543,8 +2543,21 @@
 Press Enter to edit this file in ${EDITOR} and resolve the conflicts
 manually...
 			EOF
-			read dummy </dev/tty
-			${EDITOR} `pwd`/merge/new/${F} < /dev/tty
+			while true; do
+				read dummy </dev/tty
+				${EDITOR} `pwd`/merge/new/${F} < /dev/tty
+
+				if ! egrep -q '^(<<<<<<<|=======|>>>>>>>)([[:space:]].*)?$' $(pwd)/merge/new/${F} ; then
+					break
+				fi
+				cat <<-EOF
+
+Merge conflict markers remain in: ${F}
+These must be resolved for the system to be functional.
+
+Press Enter to return to editing this file.
+				EOF
+			done
 		done < failed.merges
 		rm failed.merges