--- /dev/null
+From 8491f0dc74f8bc89bb926b8130b45eaa5ba92c4b Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@dashbit.co>
+Date: Sat, 28 Mar 2020 10:49:16 +0100
+Subject: [PATCH] Fix improper regex use, closes #9914
+
+---
+ lib/elixir/test/elixir/regex_test.exs | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+--- a/lib/elixir/test/elixir/regex_test.exs
++++ b/lib/elixir/test/elixir/regex_test.exs
+@@ -91,8 +91,10 @@ defmodule RegexTest do
+ assert <<0xA0::utf8>> =~ ~r/[[:space:]]/u
+ assert <<0xA0::utf8>> =~ ~r/\s/u
+
++ # Erlang/OTP 23 raises badarg on invalid UTF-8.
++ # Earlier versions simply would not match.
++ assert catch_error(if <<?<, 255, ?>>> =~ ~r/<.>/u, do: flunk("failed"), else: raise("failed"))
+ assert <<?<, 255, ?>>> =~ ~r/<.>/
+- refute <<?<, 255, ?>>> =~ ~r/<.>/u
+ end
+
+ test "ungreedy" do
+@@ -349,6 +351,6 @@ defmodule RegexTest do
+ end
+
+ defp matches_escaped?(string, match) do
+- Regex.match?(~r/#{Regex.escape(string)}/simxu, match)
++ Regex.match?(~r/#{Regex.escape(string)}/simx, match)
+ end
+ end
+--
+2.26.1
+