diff --git a/test/handlers/resp_h.erl b/test/handlers/resp_h.erl
index 61f714f4..d1c46e0d 100644
--- a/test/handlers/resp_h.erl
+++ b/test/handlers/resp_h.erl
@@ -46,7 +46,9 @@ do(<<"set_resp_headers">>, Req0, Opts) ->
 do(<<"set_resp_headers_list">>, Req0, Opts) ->
 	Req = cowboy_req:set_resp_headers([
 		{<<"content-type">>, <<"text/plain">>},
-		{<<"content-encoding">>, <<"compress">>}
+		{<<"test-header">>, <<"one">>},
+		{<<"content-encoding">>, <<"compress">>},
+		{<<"test-header">>, <<"two">>}
 	], Req0),
 	{ok, cowboy_req:reply(200, #{}, "OK", Req), Opts};
 do(<<"set_resp_headers_cookie">>, Req0, Opts) ->
diff --git a/test/req_SUITE.erl b/test/req_SUITE.erl
index 0ea1f96d..14e5f977 100644
--- a/test/req_SUITE.erl
+++ b/test/req_SUITE.erl
@@ -864,6 +864,7 @@ set_resp_headers(Config) ->
 	{200, Headers2, <<"OK">>} = do_get("/resp/set_resp_headers_list", Config),
 	true = lists:keymember(<<"content-type">>, 1, Headers2),
 	true = lists:keymember(<<"content-encoding">>, 1, Headers2),
+	{_, <<"one, two">>} = lists:keyfind(<<"test-header">>, 1, Headers2),
 	%% The set-cookie header is special. set_resp_cookie must be used.
 	{500, _, _} = do_maybe_h3_error3(do_get("/resp/set_resp_headers_cookie", Config)),
 	{500, _, _} = do_maybe_h3_error3(do_get("/resp/set_resp_headers_list_cookie", Config)),