diff --git a/msvc/ucxxrt.test.vcxproj b/msvc/ucxxrt.test.vcxproj
index 3403320..632cbb3 100644
--- a/msvc/ucxxrt.test.vcxproj
+++ b/msvc/ucxxrt.test.vcxproj
@@ -37,13 +37,13 @@
     <ProjectName>ucxxrt.test</ProjectName>
   </PropertyGroup>
   <PropertyGroup Label="Configuration">
-    <TargetVersion>Windows10</TargetVersion>
+    <TargetVersion>Windows7</TargetVersion>
     <UseDebugLibraries>false</UseDebugLibraries>
     <UseDebugLibraries Condition="'$(Configuration)'=='Debug'">true</UseDebugLibraries>
     <PlatformToolset>WindowsKernelModeDriver10.0</PlatformToolset>
     <ConfigurationType>Driver</ConfigurationType>
     <DriverType>WDM</DriverType>
-    <DriverTargetPlatform>Universal</DriverTargetPlatform>
+    <DriverTargetPlatform>Desktop</DriverTargetPlatform>
     <Driver_SpectreMitigation>Spectre</Driver_SpectreMitigation>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
diff --git a/src/crt/stl/xlock.cpp b/src/crt/stl/xlock.cpp
index c1d74c0..09a1df9 100644
--- a/src/crt/stl/xlock.cpp
+++ b/src/crt/stl/xlock.cpp
@@ -8,6 +8,8 @@
 #include <clocale>
 #include <cstdlib>
 
+//#pragma message(_CRT_STRINGIZE(_MSC_VER))
+
 #if _MSC_VER >= 1936 // 17.6
 #include "init_locks.hpp"
 #endif
diff --git a/src/crt/stl/xmtx.hpp b/src/crt/stl/xmtx.hpp
index 602e203..b1479a2 100644
--- a/src/crt/stl/xmtx.hpp
+++ b/src/crt/stl/xmtx.hpp
@@ -10,6 +10,10 @@
 
 //#include <Windows.h>
 
+#ifndef _RELIABILITY_CONTRACT
+#define _RELIABILITY_CONTRACT
+#endif
+
 #pragma pack(push, _CRT_PACKING)
 #pragma warning(push, 3)
 #pragma push_macro("new")
diff --git a/src/crt/stl/xnotify.cpp b/src/crt/stl/xnotify.cpp
index 543dfe8..9c832ab 100644
--- a/src/crt/stl/xnotify.cpp
+++ b/src/crt/stl/xnotify.cpp
@@ -8,6 +8,10 @@
 
 //#include <Windows.h>
 
+#if _MSC_VER < 1936 // 17.6
+#define noexcept
+#endif
+
 constexpr int _Nitems = 20;
 
 namespace {
@@ -33,7 +37,7 @@ void _Lock_at_thread_exit_mutex();
 void _Unlock_at_thread_exit_mutex();
 
 void __cdecl _Cnd_register_at_thread_exit(
-    _Cnd_t cnd, _Mtx_t mtx, int* p) { // register condition variable and mutex for cleanup at thread exit
+    _Cnd_t cnd, _Mtx_t mtx, int* p) noexcept { // register condition variable and mutex for cleanup at thread exit
     // find block with available space
     _At_thread_exit_block* block = &_Thread_exit_data;
 
@@ -62,7 +66,7 @@ void __cdecl _Cnd_register_at_thread_exit(
     _Unlock_at_thread_exit_mutex();
 }
 
-void __cdecl _Cnd_unregister_at_thread_exit(_Mtx_t mtx) { // unregister condition variable/mutex for cleanup at thread exit
+void __cdecl _Cnd_unregister_at_thread_exit(_Mtx_t mtx) noexcept { // unregister condition variable/mutex for cleanup at thread exit
     // find condition variables waiting for this thread to exit
     _At_thread_exit_block* block = &_Thread_exit_data;
 
@@ -80,7 +84,7 @@ void __cdecl _Cnd_unregister_at_thread_exit(_Mtx_t mtx) { // unregister conditio
     _Unlock_at_thread_exit_mutex();
 }
 
-void __cdecl _Cnd_do_broadcast_at_thread_exit() { // notify condition variables waiting for this thread to exit
+void __cdecl _Cnd_do_broadcast_at_thread_exit() noexcept { // notify condition variables waiting for this thread to exit
     // find condition variables waiting for this thread to exit
     _At_thread_exit_block* block       = &_Thread_exit_data;
     const unsigned int currentThreadId = _Thrd_id();
diff --git a/src/crt/stl/xtime.cpp b/src/crt/stl/xtime.cpp
index 6157a43..8c9f3ee 100644
--- a/src/crt/stl/xtime.cpp
+++ b/src/crt/stl/xtime.cpp
@@ -8,6 +8,10 @@
 
 // #include "awint.hpp"
 
+#if _MSC_VER < 1936 // 17.6
+#define noexcept
+#endif
+
 constexpr long _Nsec_per_sec = 1000000000L;
 constexpr long _Nsec_per_msec = 1000000L;
 constexpr int _Msec_per_sec = 1000;
@@ -48,27 +52,28 @@ constexpr long _Nsec100_per_sec = _Nsec_per_sec / 100;
 
 _EXTERN_C
 
-_CRTIMP2_PURE long long __cdecl _Xtime_get_ticks() { // get system time in 100-nanosecond intervals since the epoch
+_CRTIMP2_PURE long long __cdecl _Xtime_get_ticks() noexcept { // get system time in 100-nanosecond intervals since the epoch
     LARGE_INTEGER li;
-    KeQuerySystemTimePrecise(&li);
+    KeQuerySystemTime(&li);
+    //KeQuerySystemTimePrecise(&li);
     return ((static_cast<long long>(li.HighPart)) << 32) + static_cast<long long>(li.LowPart) - _Epoch;
 }
 
 // Used by several src files, but not dllexported.
-void _Timespec64_get_sys(_timespec64* xt) { // get system time with nanosecond resolution
+void _Timespec64_get_sys(_timespec64* xt) noexcept { // get system time with nanosecond resolution
     unsigned long long now = _Xtime_get_ticks();
     xt->tv_sec = static_cast<__time64_t>(now / _Nsec100_per_sec);
     xt->tv_nsec = static_cast<long>(now % _Nsec100_per_sec) * 100;
 }
 
 // convert time to milliseconds
-_CRTIMP2_PURE long __cdecl _Xtime_diff_to_millis2(const _timespec64* xt1, const _timespec64* xt2) {
+_CRTIMP2_PURE long __cdecl _Xtime_diff_to_millis2(const _timespec64* xt1, const _timespec64* xt2) noexcept {
     _timespec64 diff = _timespec64_diff(xt1, xt2);
     return static_cast<long>(diff.tv_sec * _Msec_per_sec + (diff.tv_nsec + _Nsec_per_msec - 1) / _Nsec_per_msec);
 }
 
 // TRANSITION, ABI: preserved for binary compatibility
-_CRTIMP2_PURE long __cdecl _Xtime_diff_to_millis(const _timespec64* xt) { // convert time to milliseconds
+_CRTIMP2_PURE long __cdecl _Xtime_diff_to_millis(const _timespec64* xt) noexcept { // convert time to milliseconds
     _timespec64 now;
     _Timespec64_get_sys(&now);
     return _Xtime_diff_to_millis2(xt, &now);
@@ -86,13 +91,13 @@ _CRTIMP2_PURE int __cdecl xtime_get(_timespec64* xt, int type) { // get current
     return type;
 }
 
-_CRTIMP2_PURE long long __cdecl _Query_perf_counter() { // get current value of performance counter
+_CRTIMP2_PURE long long __cdecl _Query_perf_counter() noexcept { // get current value of performance counter
     LARGE_INTEGER li;
     KeQueryPerformanceCounter(&li); // always succeeds
     return li.QuadPart;
 }
 
-_CRTIMP2_PURE long long __cdecl _Query_perf_frequency() { // get frequency of performance counter
+_CRTIMP2_PURE long long __cdecl _Query_perf_frequency() noexcept { // get frequency of performance counter
     static std::atomic<long long> freq_cached{ 0 };
     long long freq = freq_cached.load(std::memory_order_relaxed);
     if (freq == 0) {