diff --git a/flow/Arena.cpp b/flow/Arena.cpp
index 77ea8f1055..ae4a0fb2ca 100644
--- a/flow/Arena.cpp
+++ b/flow/Arena.cpp
@@ -613,3 +613,40 @@ TEST_CASE("/flow/Arena/SmallVectorRef10") {
 	testVectorLike<SmallVectorRef10Proxy>();
 	return Void();
 }
+
+TEST_CASE("/flow/Arena/OptionalHash") {
+	std::hash<Optional<int>> hashFunc{};
+	Optional<int> a;
+	Optional<int> b;
+	Optional<int> c = 1;
+	Optional<int> d = 1;
+	Optional<int> e = 2;
+
+	ASSERT(hashFunc(a) == hashFunc(b));
+	ASSERT(hashFunc(a) != hashFunc(c));
+	ASSERT(hashFunc(c) == hashFunc(d));
+	ASSERT(hashFunc(c) != hashFunc(e));
+	ASSERT(hashFunc(a) == hashFunc(a));
+	ASSERT(hashFunc(c) == hashFunc(c));
+
+	return Void();
+}
+
+TEST_CASE("/flow/Arena/DefaultBoostHash") {
+	boost::hash<std::pair<Optional<int>, StringRef>> hashFunc;
+
+	auto a = std::make_pair(Optional<int>(), "foo"_sr);
+	auto b = std::make_pair(Optional<int>(), "foo"_sr);
+	auto c = std::make_pair(Optional<int>(), "bar"_sr);
+	auto d = std::make_pair(Optional<int>(1), "foo"_sr);
+	auto e = std::make_pair(Optional<int>(1), "foo"_sr);
+
+	ASSERT(hashFunc(a) == hashFunc(b));
+	ASSERT(hashFunc(a) != hashFunc(c));
+	ASSERT(hashFunc(a) != hashFunc(d));
+	ASSERT(hashFunc(d) == hashFunc(e));
+	ASSERT(hashFunc(a) == hashFunc(a));
+	ASSERT(hashFunc(d) == hashFunc(d));
+
+	return Void();
+}
\ No newline at end of file