diff --git a/hphp/test/slow/open_tuples/tuple_open_sub.php b/hphp/test/slow/open_tuples/tuple_open_sub.php
new file mode 100644
index 0000000000000..da2dc43531f3d
--- /dev/null
+++ b/hphp/test/slow/open_tuples/tuple_open_sub.php
@@ -0,0 +1,46 @@
+<?hh
+
+<<file: __EnableUnstableFeatures('open_tuples')>>
+
+function expectAnyTuple((mixed...) $x): void {
+  var_dump($x);
+}
+function expectAnyArraykeyTuple((arraykey...) $x): void {
+  expectAnyTuple($x);
+  var_dump($x);
+}
+function expectAtLeastInt((int, mixed...) $x): void {
+  expectAnyTuple($x);
+  var_dump($x);
+}
+function expectIntThenMaybeString((int, optional string) $x): void {
+  expectAnyTuple($x);
+  expectAnyArraykeyTuple($x);
+  var_dump($x);
+}
+function expectIntThenMaybeArraykeyThenMaybeBool(
+  (int, optional arraykey, optional bool) $x,
+): void {
+  expectAnyTuple($x);
+  expectAtLeastInt($x);
+  var_dump($x);
+}
+
+<<__EntryPoint>>
+function test_closed_sub(): void {
+  $none = tuple();
+  $one = tuple(1);
+  $two = tuple(1, 'a');
+  expectAnyTuple($none);
+  expectAnyTuple($one);
+  expectAnyTuple($two);
+  expectAnyArraykeyTuple($none);
+  expectAnyArraykeyTuple($one);
+  expectAnyArraykeyTuple($two);
+  expectAtLeastInt($one);
+  expectAtLeastInt($two);
+  expectIntThenMaybeString($one);
+  expectIntThenMaybeString($two);
+  expectIntThenMaybeArraykeyThenMaybeBool($one);
+  expectIntThenMaybeArraykeyThenMaybeBool($two);
+}
diff --git a/hphp/test/slow/open_tuples/tuple_open_sub.php.expect b/hphp/test/slow/open_tuples/tuple_open_sub.php.expect
new file mode 100644
index 0000000000000..6cd6be96c16ab
--- /dev/null
+++ b/hphp/test/slow/open_tuples/tuple_open_sub.php.expect
@@ -0,0 +1,97 @@
+vec(0) {
+}
+vec(1) {
+  int(1)
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(0) {
+}
+vec(0) {
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(1) {
+  int(1)
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
+vec(2) {
+  int(1)
+  string(1) "a"
+}
diff --git a/hphp/test/slow/open_tuples/tuple_open_sub.php.hphp_opts b/hphp/test/slow/open_tuples/tuple_open_sub.php.hphp_opts
new file mode 100644
index 0000000000000..027f3ed6b1330
--- /dev/null
+++ b/hphp/test/slow/open_tuples/tuple_open_sub.php.hphp_opts
@@ -0,0 +1 @@
+-vRuntime.Hack.Lang.AllowUnstableFeatures=1
diff --git a/hphp/test/slow/open_tuples/tuple_open_sub.php.opts b/hphp/test/slow/open_tuples/tuple_open_sub.php.opts
new file mode 100644
index 0000000000000..1f2bf3d662130
--- /dev/null
+++ b/hphp/test/slow/open_tuples/tuple_open_sub.php.opts
@@ -0,0 +1 @@
+-vHack.Lang.AllowUnstableFeatures=1