diff --git a/include/ftl/details/future.h b/include/ftl/details/future.h
new file mode 100644
index 0000000..df1323e
--- /dev/null
+++ b/include/ftl/details/future.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+namespace android::ftl {
+
+template <typename, template <typename> class>
+class Future;
+
+namespace details {
+
+template <typename T>
+struct future_result {
+  using type = T;
+};
+
+template <typename T>
+struct future_result<std::future<T>> {
+  using type = T;
+};
+
+template <typename T>
+struct future_result<std::shared_future<T>> {
+  using type = T;
+};
+
+template <typename T, template <typename> class FutureImpl>
+struct future_result<Future<T, FutureImpl>> {
+  using type = T;
+};
+
+template <typename T>
+using future_result_t = typename future_result<T>::type;
+
+struct ValueTag {};
+
+template <typename, typename T, template <typename> class>
+class BaseFuture;
+
+template <typename Self, typename T>
+class BaseFuture<Self, T, std::future> {
+  using Impl = std::future<T>;
+
+ public:
+  Future<T, std::shared_future> share() {
+    if (T* value = std::get_if<T>(&self())) {
+      return {ValueTag{}, std::move(*value)};
+    }
+
+    return std::get<Impl>(self()).share();
+  }
+
+ protected:
+  T get() {
+    if (T* value = std::get_if<T>(&self())) {
+      return std::move(*value);
+    }
+
+    return std::get<Impl>(self()).get();
+  }
+
+ private:
+  auto& self() { return static_cast<Self&>(*this).future_; }
+};
+
+template <typename Self, typename T>
+class BaseFuture<Self, T, std::shared_future> {
+  using Impl = std::shared_future<T>;
+
+ protected:
+  const T& get() const {
+    if (const T* value = std::get_if<T>(&self())) {
+      return *value;
+    }
+
+    return std::get<Impl>(self()).get();
+  }
+
+ private:
+  const auto& self() const { return static_cast<const Self&>(*this).future_; }
+};
+
+}  // namespace details
+}  // namespace android::ftl