diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
new file mode 100644
index 00000000..ef903269
--- /dev/null
+++ b/src/CMakeLists.txt
@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.13)
+project(calculator CXX)
+set(CMAKE_CXX_STANDARD 17)
+
+if(CMAKE_CXX_COMPILER MATCHES ".*clang")
+    # Clang disagress with libstdc++ about constexpr-ness of wstring_view
+    # See https://github.com/Microsoft/calculator/pull/321
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
+endif()
+
+add_subdirectory(CalcManager)
diff --git a/src/CalcManager/CEngine/CMakeLists.txt b/src/CalcManager/CEngine/CMakeLists.txt
new file mode 100644
index 00000000..ba4348ff
--- /dev/null
+++ b/src/CalcManager/CEngine/CMakeLists.txt
@@ -0,0 +1,14 @@
+target_sources(CalcManager PRIVATE
+	calc.cpp
+	CalcInput.cpp
+	CalcUtils.cpp
+	History.cpp
+	Number.cpp
+	Rational.cpp
+	RationalMath.cpp
+	scicomm.cpp
+	scidisp.cpp
+	scifunc.cpp
+	scioper.cpp
+	sciset.cpp
+)
diff --git a/src/CalcManager/CEngine/Rational.cpp b/src/CalcManager/CEngine/Rational.cpp
index a0bcd97d..8eb4a91a 100644
--- a/src/CalcManager/CEngine/Rational.cpp
+++ b/src/CalcManager/CEngine/Rational.cpp
@@ -1,6 +1,5 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 
-#include <intsafe.h>
 #include "Header Files/Rational.h"
 
 using namespace std;
@@ -53,8 +52,8 @@ namespace CalcEngine
 
     Rational::Rational(uint64_t ui)
     {
-        uint32_t hi = HIDWORD(ui);
-        uint32_t lo = LODWORD(ui);
+        uint32_t hi = (uint32_t) (((ui) >> 32) & 0xffffffff);
+        uint32_t lo = (uint32_t) ui;
 
         Rational temp = (Rational{ hi } << 32) | lo;
 
diff --git a/src/CalcManager/CMakeLists.txt b/src/CalcManager/CMakeLists.txt
new file mode 100644
index 00000000..c02bc78d
--- /dev/null
+++ b/src/CalcManager/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_library(CalcManager
+	CalculatorHistory.cpp
+	CalculatorManager.cpp
+	ExpressionCommand.cpp
+	pch.cpp
+	UnitConverter.cpp
+)
+target_include_directories(CalcManager PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+add_subdirectory(Ratpack)
+add_subdirectory(CEngine)
diff --git a/src/CalcManager/CalculatorManager.cpp b/src/CalcManager/CalculatorManager.cpp
index d054f5b1..e09d7d90 100644
--- a/src/CalcManager/CalculatorManager.cpp
+++ b/src/CalcManager/CalculatorManager.cpp
@@ -12,6 +12,10 @@ using namespace CalcEngine;
 static constexpr size_t MAX_HISTORY_ITEMS = 20;
 static constexpr size_t SERIALIZED_NUMBER_MINSIZE = 3;
 
+#ifndef _MSC_VER
+#define __pragma(x)
+#endif
+
 // Converts Memory Command enum value to unsigned char,
 // while ignoring Warning C4309: 'conversion' : truncation of constant value
 #define MEMORY_COMMAND_TO_UNSIGNED_CHAR(c) __pragma(warning(push)) __pragma(warning(disable : 4309)) static_cast<unsigned char>(c) __pragma(warning(pop))
diff --git a/src/CalcManager/CalculatorVector.h b/src/CalcManager/CalculatorVector.h
index e89b55e4..bd82abbc 100644
--- a/src/CalcManager/CalculatorVector.h
+++ b/src/CalcManager/CalculatorVector.h
@@ -5,10 +5,10 @@
 
 #include <string>
 #include <vector>
-#include <winerror.h>
+#include "winerror_cross_platform.h"
 #include "Ratpack/CalcErr.h"
 #include <stdexcept> // for std::out_of_range
-#include <sal.h>     // for SAL
+#include "sal_cross_platform.h"     // for SAL
 
 template <typename TType>
 class CalculatorVector
diff --git a/src/CalcManager/Header Files/EngineStrings.h b/src/CalcManager/Header Files/EngineStrings.h
index a85fc508..fffebf0d 100644
--- a/src/CalcManager/Header Files/EngineStrings.h	
+++ b/src/CalcManager/Header Files/EngineStrings.h	
@@ -16,7 +16,10 @@
 
 #pragma once
 
+#include <array>
 #include <string>
+#include <string_view>
+#include <unordered_map>
 
 inline constexpr auto IDS_ERRORS_FIRST = 99;
 
diff --git a/src/CalcManager/Ratpack/CMakeLists.txt b/src/CalcManager/Ratpack/CMakeLists.txt
new file mode 100644
index 00000000..3fbd7ae3
--- /dev/null
+++ b/src/CalcManager/Ratpack/CMakeLists.txt
@@ -0,0 +1,14 @@
+target_sources(CalcManager PRIVATE
+	basex.cpp
+	conv.cpp
+	exp.cpp
+	fact.cpp
+	itrans.cpp
+	itransh.cpp
+	logic.cpp
+	num.cpp
+	rat.cpp
+	support.cpp
+	trans.cpp
+	transh.cpp
+)
diff --git a/src/CalcManager/Ratpack/conv.cpp b/src/CalcManager/Ratpack/conv.cpp
index 9a944ea5..d96fe306 100644
--- a/src/CalcManager/Ratpack/conv.cpp
+++ b/src/CalcManager/Ratpack/conv.cpp
@@ -18,7 +18,7 @@
 //---------------------------------------------------------------------------
 
 #include <algorithm>
-#include <winerror.h>
+#include "winerror_cross_platform.h"
 #include <sstream>
 #include <cstring> // for memmove, memcpy
 #include "ratpak.h"
diff --git a/src/CalcManager/Ratpack/ratpak.h b/src/CalcManager/Ratpack/ratpak.h
index 2e7c973c..dc6a98d9 100644
--- a/src/CalcManager/Ratpack/ratpak.h
+++ b/src/CalcManager/Ratpack/ratpak.h
@@ -21,7 +21,7 @@
 #include <string>
 #include "CalcErr.h"
 #include <cstring> // for memmove
-#include <sal.h>   // for SAL
+#include "sal_cross_platform.h"   // for SAL
 
 static constexpr uint32_t BASEXPWR = 31L;     // Internal log2(BASEX)
 static constexpr uint32_t BASEX = 0x80000000; // Internal radix used in calculations, hope to raise
diff --git a/src/CalcManager/UnitConverter.cpp b/src/CalcManager/UnitConverter.cpp
index 57cd49bd..bbf761ba 100644
--- a/src/CalcManager/UnitConverter.cpp
+++ b/src/CalcManager/UnitConverter.cpp
@@ -2,12 +2,12 @@
 // Licensed under the MIT License.
 
 #include <cassert>
+#include <cmath>
 #include <sstream>
 #include <algorithm> // for std::sort
 #include "Command.h"
 #include "UnitConverter.h"
 
-using namespace concurrency;
 using namespace std;
 using namespace UnitConversionManager;
 
@@ -229,7 +229,7 @@ Unit UnitConverter::StringToUnit(const wstring& w)
     vector<wstring> tokenList = StringToVector(w, L";");
     assert(tokenList.size() == EXPECTEDSERIALIZEDUNITTOKENCOUNT);
     Unit serializedUnit;
-    serializedUnit.id = _wtoi(Unquote(tokenList[0]).c_str());
+    serializedUnit.id = wcstol(Unquote(tokenList[0]).c_str(), nullptr, 10);
     serializedUnit.name = Unquote(tokenList[1]);
     serializedUnit.accessibleName = serializedUnit.name;
     serializedUnit.abbreviation = Unquote(tokenList[2]);
@@ -244,7 +244,7 @@ Category UnitConverter::StringToCategory(const wstring& w)
     vector<wstring> tokenList = StringToVector(w, L";");
     assert(tokenList.size() == EXPECTEDSERIALIZEDCATEGORYTOKENCOUNT);
     Category serializedCategory;
-    serializedCategory.id = _wtoi(Unquote(tokenList[0]).c_str());
+    serializedCategory.id = wcstol(Unquote(tokenList[0]).c_str(), nullptr, 10);
     serializedCategory.supportsNegative = (tokenList[1].compare(L"1") == 0);
     serializedCategory.name = Unquote(tokenList[2]);
     return serializedCategory;
@@ -536,30 +536,31 @@ void UnitConverter::SetViewModelCurrencyCallback(_In_ const shared_ptr<IViewMode
     }
 }
 
-task<pair<bool, wstring>> UnitConverter::RefreshCurrencyRatios()
+future<pair<bool, wstring>> UnitConverter::RefreshCurrencyRatios()
 {
     shared_ptr<ICurrencyConverterDataLoader> currencyDataLoader = GetCurrencyConverterDataLoader();
-    return create_task([this, currencyDataLoader]() {
-               if (currencyDataLoader != nullptr)
-               {
-                   return currencyDataLoader->TryLoadDataFromWebOverrideAsync();
-               }
-               else
-               {
-                   return task_from_result(false);
-               }
-           })
-        .then(
-            [this, currencyDataLoader](bool didLoad) {
-                wstring timestamp = L"";
-                if (currencyDataLoader != nullptr)
-                {
-                    timestamp = currencyDataLoader->GetCurrencyTimestamp();
-                }
+    future<bool> loadDataResult;
+    if (currencyDataLoader != nullptr)
+    {
+        loadDataResult = currencyDataLoader->TryLoadDataFromWebOverrideAsync();
+    }
+    else
+    {
+        loadDataResult = async([] { return false; });
+    }
 
-                return make_pair(didLoad, timestamp);
-            },
-            task_continuation_context::use_default());
+    shared_future<bool> sharedLoadResult = loadDataResult.share();
+    return async([this, currencyDataLoader, sharedLoadResult]() {
+        sharedLoadResult.wait();
+        bool didLoad = sharedLoadResult.get();
+        wstring timestamp = L"";
+        if (currencyDataLoader != nullptr)
+        {
+            timestamp = currencyDataLoader->GetCurrencyTimestamp();
+        }
+
+        return make_pair(didLoad, timestamp);
+    });
 }
 
 shared_ptr<ICurrencyConverterDataLoader> UnitConverter::GetCurrencyConverterDataLoader()
diff --git a/src/CalcManager/UnitConverter.h b/src/CalcManager/UnitConverter.h
index 19582245..0d1b8acd 100644
--- a/src/CalcManager/UnitConverter.h
+++ b/src/CalcManager/UnitConverter.h
@@ -5,8 +5,8 @@
 
 #include <vector>
 #include <unordered_map>
-#include <ppltasks.h>
-#include <sal.h>  // for SAL
+#include <future>
+#include "sal_cross_platform.h"  // for SAL
 #include <memory> // for std::shared_ptr
 
 namespace UnitConversionManager
@@ -211,9 +211,9 @@ namespace UnitConversionManager
         GetCurrencyRatioEquality(_In_ const UnitConversionManager::Unit& unit1, _In_ const UnitConversionManager::Unit& unit2) = 0;
         virtual std::wstring GetCurrencyTimestamp() = 0;
 
-        virtual concurrency::task<bool> TryLoadDataFromCacheAsync() = 0;
-        virtual concurrency::task<bool> TryLoadDataFromWebAsync() = 0;
-        virtual concurrency::task<bool> TryLoadDataFromWebOverrideAsync() = 0;
+        virtual std::future<bool> TryLoadDataFromCacheAsync() = 0;
+        virtual std::future<bool> TryLoadDataFromWebAsync() = 0;
+        virtual std::future<bool> TryLoadDataFromWebOverrideAsync() = 0;
     };
 
     class IUnitConverterVMCallback
@@ -242,7 +242,7 @@ namespace UnitConversionManager
         virtual void SendCommand(Command command) = 0;
         virtual void SetViewModelCallback(_In_ const std::shared_ptr<IUnitConverterVMCallback>& newCallback) = 0;
         virtual void SetViewModelCurrencyCallback(_In_ const std::shared_ptr<IViewModelCurrencyCallback>& newCallback) = 0;
-        virtual concurrency::task<std::pair<bool, std::wstring>> RefreshCurrencyRatios() = 0;
+        virtual std::future<std::pair<bool, std::wstring>> RefreshCurrencyRatios() = 0;
         virtual void Calculate() = 0;
         virtual void ResetCategoriesAndRatios() = 0;
     };
@@ -265,7 +265,7 @@ namespace UnitConversionManager
         void SendCommand(Command command) override;
         void SetViewModelCallback(_In_ const std::shared_ptr<IUnitConverterVMCallback>& newCallback) override;
         void SetViewModelCurrencyCallback(_In_ const std::shared_ptr<IViewModelCurrencyCallback>& newCallback) override;
-        concurrency::task<std::pair<bool, std::wstring>> RefreshCurrencyRatios() override;
+        std::future<std::pair<bool, std::wstring>> RefreshCurrencyRatios() override;
         void Calculate() override;
         void ResetCategoriesAndRatios() override;
         // IUnitConverter
diff --git a/src/CalcManager/pch.h b/src/CalcManager/pch.h
index e66e1a38..2bcedb7a 100644
--- a/src/CalcManager/pch.h
+++ b/src/CalcManager/pch.h
@@ -13,7 +13,7 @@
 #include <cassert>
 #include <intsafe.h>
 #include <list>
-#include <ppltasks.h>
+#include <future>
 #include <regex>
 #include <sstream>
 #include <string>
diff --git a/src/CalcManager/sal_cross_platform.h b/src/CalcManager/sal_cross_platform.h
new file mode 100644
index 00000000..416bf096
--- /dev/null
+++ b/src/CalcManager/sal_cross_platform.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#if defined(_WIN32) && defined(_MSC_VER)
+
+#include <sal.h>
+
+#else
+
+// Empty macro definitions for source annotations
+
+#define _In_opt_
+#define _Out_opt_
+#define _In_
+#define _Out_
+#define _Inout_
+#define __in_opt
+#define _Frees_ptr_opt_
+
+#endif
diff --git a/src/CalcManager/winerror_cross_platform.h b/src/CalcManager/winerror_cross_platform.h
new file mode 100644
index 00000000..07b6cd3f
--- /dev/null
+++ b/src/CalcManager/winerror_cross_platform.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#if defined(_WIN32) && defined(_MSC_VER)
+
+#include <winerror.h>
+
+#else
+
+#include "Ratpack/CalcErr.h"
+
+#define E_ACCESSDENIED 0x80070005
+#define E_FAIL 0x80004005
+#define E_INVALIDARG 0x80070057
+#define E_OUTOFMEMORY 0x8007000E
+#define E_POINTER 0x80004003
+#define E_UNEXPECTED 0x8000FFFF
+#define E_BOUNDS 0x8000000B
+#define S_OK 0x0
+#define S_FALSE 0x1
+
+#define SUCCEEDED(hr) (((ResultCode)(hr)) >= 0)
+#define FAILED(hr) (((ResultCode)(hr)) < 0)
+#define SCODE_CODE(sc) ((sc) & 0xFFFF)
+
+#endif
diff --git a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
index d51a1940..2e7cc3cc 100644
--- a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
+++ b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.cpp
@@ -191,7 +191,7 @@ void CurrencyDataLoader::LoadData()
     if (!LoadFinished())
     {
         create_task([this]() -> task<bool> {
-            vector<function<task<bool>()>> loadFunctions = {
+            vector<function<future<bool>()>> loadFunctions = {
                 [this]() { return TryLoadDataFromCacheAsync(); },
                 [this]() { return TryLoadDataFromWebAsync(); },
             };
@@ -307,7 +307,7 @@ pair<wstring, wstring> CurrencyDataLoader::GetCurrencyRatioEquality(_In_ const U
 }
 
 #pragma optimize("", off) // Turn off optimizations to work around DevDiv 393321
-task<bool> CurrencyDataLoader::TryLoadDataFromCacheAsync()
+future<bool> CurrencyDataLoader::TryLoadDataFromCacheAsync()
 {
     try
     {
@@ -349,7 +349,7 @@ task<bool> CurrencyDataLoader::TryLoadDataFromCacheAsync()
     }
 }
 
-task<bool> CurrencyDataLoader::TryFinishLoadFromCacheAsync()
+future<bool> CurrencyDataLoader::TryFinishLoadFromCacheAsync()
 {
     auto localSettings = ApplicationData::Current->LocalSettings;
     if (localSettings == nullptr)
@@ -386,7 +386,7 @@ task<bool> CurrencyDataLoader::TryFinishLoadFromCacheAsync()
     co_return true;
 }
 
-task<bool> CurrencyDataLoader::TryLoadDataFromWebAsync()
+future<bool> CurrencyDataLoader::TryLoadDataFromWebAsync()
 {
     try
     {
@@ -459,7 +459,7 @@ task<bool> CurrencyDataLoader::TryLoadDataFromWebAsync()
     }
 }
 
-task<bool> CurrencyDataLoader::TryLoadDataFromWebOverrideAsync()
+future<bool> CurrencyDataLoader::TryLoadDataFromWebOverrideAsync()
 {
     m_meteredOverrideSet = true;
     bool didLoad = co_await TryLoadDataFromWebAsync();
diff --git a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.h b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.h
index 1ec031d1..a4be2d0e 100644
--- a/src/CalcViewModel/DataLoaders/CurrencyDataLoader.h
+++ b/src/CalcViewModel/DataLoaders/CurrencyDataLoader.h
@@ -76,9 +76,9 @@ namespace CalculatorApp
             GetCurrencyRatioEquality(_In_ const UnitConversionManager::Unit& unit1, _In_ const UnitConversionManager::Unit& unit2) override;
             std::wstring GetCurrencyTimestamp() override;
 
-            concurrency::task<bool> TryLoadDataFromCacheAsync() override;
-            concurrency::task<bool> TryLoadDataFromWebAsync() override;
-            concurrency::task<bool> TryLoadDataFromWebOverrideAsync() override;
+            std::future<bool> TryLoadDataFromCacheAsync() override;
+            std::future<bool> TryLoadDataFromWebAsync() override;
+            std::future<bool> TryLoadDataFromWebOverrideAsync() override;
             // ICurrencyConverterDataLoader
 
             void OnNetworkBehaviorChanged(CalculatorApp::NetworkAccessBehavior newBehavior);
@@ -87,7 +87,7 @@ namespace CalculatorApp
             void ResetLoadStatus();
             void NotifyDataLoadFinished(bool didLoad);
 
-            concurrency::task<bool> TryFinishLoadFromCacheAsync();
+            std::future<bool> TryFinishLoadFromCacheAsync();
 
             bool TryParseWebResponses(
                 _In_ Platform::String ^ staticDataJson,
diff --git a/src/CalcViewModel/UnitConverterViewModel.cpp b/src/CalcViewModel/UnitConverterViewModel.cpp
index 72d31464..821cdc70 100644
--- a/src/CalcViewModel/UnitConverterViewModel.cpp
+++ b/src/CalcViewModel/UnitConverterViewModel.cpp
@@ -675,7 +675,7 @@ void UnitConverterViewModel::RefreshCurrencyRatios()
     String ^ announcement = AppResourceProvider::GetInstance().GetResourceString(UnitConverterResourceKeys::UpdatingCurrencyRates);
     Announcement = CalculatorAnnouncement::GetUpdateCurrencyRatesAnnouncement(announcement);
 
-    auto refreshTask = create_task(m_model->RefreshCurrencyRatios());
+    auto refreshTask = create_task([this] { return m_model->RefreshCurrencyRatios().get(); });
     refreshTask.then(
         [this](const pair<bool, wstring>& refreshResult) {
             bool didLoad = refreshResult.first;
diff --git a/src/CalculatorUnitTests/UnitConverterViewModelUnitTests.h b/src/CalculatorUnitTests/UnitConverterViewModelUnitTests.h
index 08c0f954..8601ca76 100644
--- a/src/CalculatorUnitTests/UnitConverterViewModelUnitTests.h
+++ b/src/CalculatorUnitTests/UnitConverterViewModelUnitTests.h
@@ -47,7 +47,7 @@ namespace CalculatorUnitTests
         void ResetCategoriesAndRatios() override
         {
         }
-        concurrency::task<std::pair<bool, std::wstring>> RefreshCurrencyRatios() override
+        std::future<std::pair<bool, std::wstring>> RefreshCurrencyRatios() override
         {
             co_return std::make_pair(true, L"");
         }