diff --git a/UnitTests/UnitTests.vcxproj b/UnitTests/UnitTests.vcxproj
index 6542eeac3..55a7a5d5d 100644
--- a/UnitTests/UnitTests.vcxproj
+++ b/UnitTests/UnitTests.vcxproj
@@ -82,6 +82,7 @@
..\include;$(VCInstallDir)UnitTest\include;%(AdditionalIncludeDirectories)
true
pch.h
+ stdcpp17
Windows
@@ -111,11 +112,7 @@
-
-
- stdcpp17
-
-
+
diff --git a/include/stdex/stream.hpp b/include/stdex/stream.hpp
index 7d23f0f47..92e6ade19 100644
--- a/include/stdex/stream.hpp
+++ b/include/stdex/stream.hpp
@@ -589,7 +589,7 @@ namespace stdex
inline basic& operator <<(_In_ const uint32_t data) { return write_data(data); }
inline basic& operator >>(_Out_ uint64_t& data) { return read_data(data); }
inline basic& operator <<(_In_ const uint64_t data) { return write_data(data); }
-#ifdef _NATIVE_SIZE_T_DEFINED
+#if defined(_WIN64) && defined(_NATIVE_SIZE_T_DEFINED)
inline basic& operator >>(_Out_ size_t& data) { return read_data(data); }
inline basic& operator <<(_In_ const size_t data) { return write_data(data); }
#endif
@@ -3291,7 +3291,7 @@ namespace stdex
inline void set(_In_ fpos_t offset, _In_ const uint16_t data) { set(offset, data); }
inline void set(_In_ fpos_t offset, _In_ const uint32_t data) { set(offset, data); }
inline void set(_In_ fpos_t offset, _In_ const uint64_t data) { set(offset, data); }
-#ifdef _NATIVE_SIZE_T_DEFINED
+#if defined(_WIN64) && defined(_NATIVE_SIZE_T_DEFINED)
inline void set(_In_ fpos_t offset, _In_ const size_t data) { set(offset, data); }
#endif
inline void set(_In_ fpos_t offset, _In_ const float data) { set(offset, data); }
@@ -3328,7 +3328,7 @@ namespace stdex
inline void get(_In_ fpos_t offset, _Out_ uint16_t & data) { get(offset, data); }
inline void get(_In_ fpos_t offset, _Out_ uint32_t & data) { get(offset, data); }
inline void get(_In_ fpos_t offset, _Out_ uint64_t & data) { get(offset, data); }
-#ifdef _NATIVE_SIZE_T_DEFINED
+#if defined(_WIN64) && defined(_NATIVE_SIZE_T_DEFINED)
inline void get(_In_ fpos_t offset, _Out_ size_t & data) { get(offset, data); }
#endif
inline void get(_In_ fpos_t offset, _Out_ float& data) { get(offset, data); }
@@ -3354,7 +3354,7 @@ namespace stdex
inline memory_file& operator >>(_Out_ uint32_t & data) { return read_data(data); }
inline memory_file& operator <<(_In_ const uint64_t data) { return write_data(data); }
inline memory_file& operator >>(_Out_ uint64_t & data) { return read_data(data); }
-#ifdef _NATIVE_SIZE_T_DEFINED
+#if defined(_WIN64) && defined(_NATIVE_SIZE_T_DEFINED)
inline memory_file& operator <<(_In_ const size_t data) { return write_data(data); }
inline memory_file& operator >>(_Out_ size_t & data) { return read_data(data); }
#endif