diff --git a/src/CalcManager/CEngine/CalcInput.cpp b/src/CalcManager/CEngine/CalcInput.cpp
index 01ecddcc..df5439b3 100644
--- a/src/CalcManager/CEngine/CalcInput.cpp
+++ b/src/CalcManager/CEngine/CalcInput.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 
 using namespace std;
diff --git a/src/CalcManager/CEngine/CalcUtils.cpp b/src/CalcManager/CEngine/CalcUtils.cpp
index 04882a4f..ce5eb73a 100644
--- a/src/CalcManager/CEngine/CalcUtils.cpp
+++ b/src/CalcManager/CEngine/CalcUtils.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 #include "Header Files/CalcUtils.h"
 
diff --git a/src/CalcManager/CEngine/History.cpp b/src/CalcManager/CEngine/History.cpp
index 56d1fc18..6c86ea68 100644
--- a/src/CalcManager/CEngine/History.cpp
+++ b/src/CalcManager/CEngine/History.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 #include "Command.h"
 #include "CalculatorVector.h"
diff --git a/src/CalcManager/CEngine/Number.cpp b/src/CalcManager/CEngine/Number.cpp
index 7590e6d1..dd57685f 100644
--- a/src/CalcManager/CEngine/Number.cpp
+++ b/src/CalcManager/CEngine/Number.cpp
@@ -1,6 +1,11 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/Number.h"
 
 using namespace std;
@@ -59,6 +64,13 @@ namespace CalcEngine
 
     bool Number::IsZero() const
     {
-        return all_of(m_mantissa.begin(), m_mantissa.end(), [](auto &&i) { return i == 0; });
+        for (auto const& digit : Mantissa())
+        {
+            if (digit != 0)
+            {
+                return false;
+            }
+        }
+        return true;
     }
 }
diff --git a/src/CalcManager/CEngine/Rational.cpp b/src/CalcManager/CEngine/Rational.cpp
index 64288ede..bcfed0e5 100644
--- a/src/CalcManager/CEngine/Rational.cpp
+++ b/src/CalcManager/CEngine/Rational.cpp
@@ -1,6 +1,11 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/Rational.h"
 
 using namespace std;
diff --git a/src/CalcManager/CEngine/RationalMath.cpp b/src/CalcManager/CEngine/RationalMath.cpp
index cda098b3..cf5f3e49 100644
--- a/src/CalcManager/CEngine/RationalMath.cpp
+++ b/src/CalcManager/CEngine/RationalMath.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/RationalMath.h"
 
 using namespace std;
diff --git a/src/CalcManager/CEngine/calc.cpp b/src/CalcManager/CEngine/calc.cpp
index c79c5964..92a551e2 100644
--- a/src/CalcManager/CEngine/calc.cpp
+++ b/src/CalcManager/CEngine/calc.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 
 #include "CalculatorResource.h"
diff --git a/src/CalcManager/CEngine/scicomm.cpp b/src/CalcManager/CEngine/scicomm.cpp
index e5984453..2db42f70 100644
--- a/src/CalcManager/CEngine/scicomm.cpp
+++ b/src/CalcManager/CEngine/scicomm.cpp
@@ -12,7 +12,13 @@
 *
 * Author:
 \****************************************************************************/
+
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 #include "Header Files/CalcUtils.h"
 
diff --git a/src/CalcManager/CEngine/scidisp.cpp b/src/CalcManager/CEngine/scidisp.cpp
index f495b803..de4fd715 100644
--- a/src/CalcManager/CEngine/scidisp.cpp
+++ b/src/CalcManager/CEngine/scidisp.cpp
@@ -12,7 +12,13 @@
 *
 * Author:
 \****************************************************************************/
+
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 
 using namespace std;
diff --git a/src/CalcManager/CEngine/scifunc.cpp b/src/CalcManager/CEngine/scifunc.cpp
index b094e5d0..15bd19eb 100644
--- a/src/CalcManager/CEngine/scifunc.cpp
+++ b/src/CalcManager/CEngine/scifunc.cpp
@@ -16,7 +16,13 @@
 /***                                                                    ***/
 /***                                                                    ***/
 /**************************************************************************/
+
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 
 using namespace std;
diff --git a/src/CalcManager/CEngine/sciset.cpp b/src/CalcManager/CEngine/sciset.cpp
index 44a4f644..9ae245d6 100644
--- a/src/CalcManager/CEngine/sciset.cpp
+++ b/src/CalcManager/CEngine/sciset.cpp
@@ -1,7 +1,12 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+#ifdef _WIN32
+#include "pch.h"
+#else
 #include "pch_cross_platform.h"
+#endif
+
 #include "Header Files/CalcEngine.h"
 
 using namespace CalcEngine;
diff --git a/src/CalcManager/Header Files/CalcEngine.h b/src/CalcManager/Header Files/CalcEngine.h
index 0ad8252f..48597f1c 100644
--- a/src/CalcManager/Header Files/CalcEngine.h	
+++ b/src/CalcManager/Header Files/CalcEngine.h	
@@ -14,6 +14,11 @@
 *
 \****************************************************************************/
 
+#ifndef _WIN32
+#include "win_data_types_cross_platform.h"
+#include "sal_cross_platform.h"
+#endif
+
 #include "CCommand.h"
 #include "EngineStrings.h"
 #include "../Command.h"
diff --git a/src/CalcManager/Ratpack/ratpak.h b/src/CalcManager/Ratpack/ratpak.h
index 75ac28de..82947971 100644
--- a/src/CalcManager/Ratpack/ratpak.h
+++ b/src/CalcManager/Ratpack/ratpak.h
@@ -17,6 +17,13 @@
 //
 //-----------------------------------------------------------------------------
 
+#ifndef _WIN32
+#include "win_data_types_cross_platform.h"
+#include "sal_cross_platform.h"
+#endif
+
+#include <cstdint>
+#include <string>
 #include "CalcErr.h"
 
 static constexpr uint32_t BASEXPWR = 31L;// Internal log2(BASEX)
diff --git a/src/CalcManager/pch_cross_platform.h b/src/CalcManager/pch_cross_platform.h
index d7f50364..5c0c7138 100644
--- a/src/CalcManager/pch_cross_platform.h
+++ b/src/CalcManager/pch_cross_platform.h
@@ -12,4 +12,7 @@
 // #include <intsafe.h>
 #include <array>
 // #include <ppltasks.h>
+
 #include "winerror_cross_platform.h"
+#include "win_data_types_cross_platform.h"
+#include "sal_cross_platform.h"
diff --git a/src/CalcManager/sal_cross_platform.h b/src/CalcManager/sal_cross_platform.h
index 42b51ef7..cc650f17 100644
--- a/src/CalcManager/sal_cross_platform.h
+++ b/src/CalcManager/sal_cross_platform.h
@@ -7,3 +7,4 @@
 #define _In_
 #define _Out_
 #define _Inout_
+#define __in_opt
diff --git a/src/CalcManager/win_data_types_cross_platform.h b/src/CalcManager/win_data_types_cross_platform.h
new file mode 100644
index 00000000..daa99bd6
--- /dev/null
+++ b/src/CalcManager/win_data_types_cross_platform.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include <cstdint>
+
+typedef uint64_t ULONGLONG;
+typedef int INT;
+typedef char CHAR;
+typedef long LONG;
+typedef unsigned int UINT_PTR;
+typedef unsigned long ULONG_PTR;
+typedef unsigned int ULONG32;
+typedef unsigned long DWORD;
+typedef unsigned long ULONG;
+typedef unsigned short USHORT;
+typedef wchar_t WCHAR;
+typedef unsigned short WORD;
+typedef UINT_PTR WPARAM;
+typedef ULONG_PTR DWORD_PTR;
+
+#define LOWORD(dw) ((WORD)(((DWORD_PTR)(dw)) & 0xffff))
+#define HIWORD(dw) ((WORD)((((DWORD_PTR)(dw)) >> 16) & 0xffff))
+#define LODWORD(qw) ((DWORD)(qw))
+#define HIDWORD(qw) ((DWORD)(((qw) >> 32) & 0xffffffff))
diff --git a/src/CalcManager/winerror_cross_platform.h b/src/CalcManager/winerror_cross_platform.h
index faa66de3..6961e77f 100644
--- a/src/CalcManager/winerror_cross_platform.h
+++ b/src/CalcManager/winerror_cross_platform.h
@@ -2,7 +2,8 @@
 
 #include <cstdint>
 
-#define HRESULT int32_t
+typedef int32_t HRESULT;
+
 #define E_ACCESSDENIED 0x80070005
 #define E_FAIL 0x80004005
 #define E_INVALIDARG 0x80070057
@@ -14,3 +15,4 @@
 #define S_FALSE 0x1
 
 #define SUCCEEDED(hr) (((HRESULT)(hr)) >= 0)
+#define FAILED(hr) (((HRESULT)(hr)) < 0)