diff --git a/UsbDk/DeviceAccess.cpp b/UsbDk/DeviceAccess.cpp
index ae99235..48183e8 100644
--- a/UsbDk/DeviceAccess.cpp
+++ b/UsbDk/DeviceAccess.cpp
@@ -22,7 +22,7 @@ PWCHAR CWdfDeviceAccess::QueryBusID(BUS_QUERY_ID_TYPE idType)
 {
     UNREFERENCED_PARAMETER(idType);
     ASSERT(!"NOT IMPLEMENTED");
-    return NULL;
+    return nullptr;
 }
 
 NTSTATUS CWdfDeviceAccess::QueryCapabilities(DEVICE_CAPABILITIES &Capabilities)
@@ -48,7 +48,7 @@ CMemoryBuffer *CWdfDeviceAccess::GetDeviceProperty(DEVICE_REGISTRY_PROPERTY prop
         return CMemoryBuffer::GetMemoryBuffer(devProperty);
     }
 
-    return NULL;
+    return nullptr;
 }
 
 PWCHAR CWdmDeviceAccess::QueryBusID(BUS_QUERY_ID_TYPE idType)
@@ -60,7 +60,7 @@ PWCHAR CWdmDeviceAccess::QueryBusID(BUS_QUERY_ID_TYPE idType)
     if (!NT_SUCCESS(status))
     {
         TraceEvents(TRACE_LEVEL_ERROR, TRACE_DEVACCESS, "%!FUNC! Error %!STATUS! during IRP creation", status);
-        return NULL;
+        return nullptr;
     }
 
     irp.Configure([idType] (PIO_STACK_LOCATION s)
@@ -75,7 +75,7 @@ PWCHAR CWdmDeviceAccess::QueryBusID(BUS_QUERY_ID_TYPE idType)
     if (!NT_SUCCESS(status))
     {
         TraceEvents(TRACE_LEVEL_ERROR, TRACE_DEVACCESS, "%!FUNC! Error %!STATUS! during %!devid! query", status, idType);
-        return NULL;
+        return nullptr;
     }
 
     PWCHAR idData;
@@ -151,8 +151,8 @@ CMemoryBuffer *CWdmDeviceAccess::GetDeviceProperty(DEVICE_REGISTRY_PROPERTY prop
 
     PAGED_CODE();
 
-    ULONG bytesNeeded = NULL;
-    auto status = IoGetDeviceProperty(m_DevObj, propertyId, 0, NULL, &bytesNeeded);
+    ULONG bytesNeeded = 0;
+    auto status = IoGetDeviceProperty(m_DevObj, propertyId, 0, nullptr, &bytesNeeded);
 
     if (!NT_SUCCESS(status))
     {
@@ -191,10 +191,10 @@ CMemoryBuffer *CWdmDeviceAccess::GetDeviceProperty(DEVICE_REGISTRY_PROPERTY prop
     {
         TraceEvents(TRACE_LEVEL_INFORMATION, TRACE_DEVACCESS,
             "%!FUNC! Empty property read for device 0x%p, %!devprop!", m_DevObj, propertyId);
-        return CMemoryBuffer::GetMemoryBuffer(NULL, 0);
+        return CMemoryBuffer::GetMemoryBuffer(nullptr, 0);
     }
 
-    return NULL;
+    return nullptr;
 }
 
 NTSTATUS CWdmUsbDeviceAccess::Reset()
diff --git a/UsbDk/WdfDevice.h b/UsbDk/WdfDevice.h
index ddac106..0a31252 100644
--- a/UsbDk/WdfDevice.h
+++ b/UsbDk/WdfDevice.h
@@ -49,7 +49,7 @@ public:
 
     NTSTATUS SetPreprocessCallback(PFN_WDFDEVICE_WDM_IRP_PREPROCESS Callback, UCHAR MajorFunction)
     {
-        return SetPreprocessCallback(Callback, MajorFunction, NULL, 0);
+        return SetPreprocessCallback(Callback, MajorFunction, nullptr, 0);
     }
 
     void SetIoInCallerContextCallback(PFN_WDF_IO_IN_CALLER_CONTEXT Callback)
diff --git a/UsbDkHelper/DeviceMgr.cpp b/UsbDkHelper/DeviceMgr.cpp
index e573fe1..5caeb0d 100644
--- a/UsbDkHelper/DeviceMgr.cpp
+++ b/UsbDkHelper/DeviceMgr.cpp
@@ -5,7 +5,7 @@
 
 InstallResult DeviceMgr::ResetDeviceByClass(const GUID &ClassGuid)
 {
-    auto hDevInfo = SetupDiGetClassDevsEx(&ClassGuid, NULL, NULL, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT, NULL, NULL, NULL);
+    auto hDevInfo = SetupDiGetClassDevsEx(&ClassGuid, nullptr, nullptr, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT, nullptr, nullptr, nullptr);
     if (hDevInfo == INVALID_HANDLE_VALUE)
     {
         throw UsbDkDeviceMgrException(TEXT("SetupDiGetClassDevsEx() failed!!"));
diff --git a/UsbDkHelper/DriverFile.cpp b/UsbDkHelper/DriverFile.cpp
index 01b5f8d..ecd1fc0 100644
--- a/UsbDkHelper/DriverFile.cpp
+++ b/UsbDkHelper/DriverFile.cpp
@@ -8,10 +8,10 @@ UsbDkDriverFile::UsbDkDriverFile(LPCTSTR lpFileName)
     m_hDriver = CreateFile(lpFileName,
                            GENERIC_READ | GENERIC_WRITE,
                            0,
-                           NULL,
+                           nullptr,
                            OPEN_EXISTING,
                            FILE_ATTRIBUTE_NORMAL,
-                           NULL);
+                           nullptr);
 
     if (m_hDriver == INVALID_HANDLE_VALUE)
     {
diff --git a/UsbDkHelper/Exception.cpp b/UsbDkHelper/Exception.cpp
index 6967429..3e525d1 100644
--- a/UsbDkHelper/Exception.cpp
+++ b/UsbDkHelper/Exception.cpp
@@ -131,12 +131,12 @@ tstring UsbDkW32ErrorException::GetErrorString(DWORD dwErrorCode)
                                     FORMAT_MESSAGE_FROM_SYSTEM |
                                     FORMAT_MESSAGE_IGNORE_INSERTS|
                                     FORMAT_MESSAGE_MAX_WIDTH_MASK,
-                                    NULL,
+                                    nullptr,
                                     dwErrorCode,
                                     MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
                                     (LPTSTR) &lpMsgBuf,
                                     0,
-                                    NULL);
+                                    nullptr);
     if(msgLen == 0)
     {
         tstringstream strm;
diff --git a/UsbDkHelper/Installer.cpp b/UsbDkHelper/Installer.cpp
index 2bbd25c..2794e75 100644
--- a/UsbDkHelper/Installer.cpp
+++ b/UsbDkHelper/Installer.cpp
@@ -123,7 +123,7 @@ void UsbDkInstaller::addUsbDkToRegistry()
 
     // check for value size
     DWORD valLen = 0;
-    auto errCode = m_regAccess.ReadMultiString(upperFilterString, NULL, 0, valLen, upperFiltersKeyStr);
+    auto errCode = m_regAccess.ReadMultiString(upperFilterString, nullptr, 0, valLen, upperFiltersKeyStr);
 
     if (errCode != ERROR_FILE_NOT_FOUND && errCode != ERROR_SUCCESS)
     {
@@ -170,7 +170,7 @@ void UsbDkInstaller::removeUsbDkFromRegistry()
 
     // check for value size
     DWORD valLen = 0;
-    auto errCode = m_regAccess.ReadMultiString(upperFilterString, NULL, 0, valLen, upperFiltersKeyStr);
+    auto errCode = m_regAccess.ReadMultiString(upperFilterString, nullptr, 0, valLen, upperFiltersKeyStr);
 
     if (errCode != ERROR_FILE_NOT_FOUND && errCode != ERROR_SUCCESS)
     {
diff --git a/UsbDkHelper/RegAccess.cpp b/UsbDkHelper/RegAccess.cpp
index 043e83c..913aa68 100644
--- a/UsbDkHelper/RegAccess.cpp
+++ b/UsbDkHelper/RegAccess.cpp
@@ -10,12 +10,12 @@
 //////////////////////////////////////////////////////////////////////
 
 UsbDkRegAccess::UsbDkRegAccess()
-    : m_lpsRegPath(NULL), m_hkPrimaryHKey(0)
+    : m_lpsRegPath(nullptr), m_hkPrimaryHKey(0)
 {
 }
 
 UsbDkRegAccess::UsbDkRegAccess(HKEY hNewPrKey, LPCTSTR lpzNewRegPath)
-    : m_lpsRegPath(NULL), m_hkPrimaryHKey(0)
+    : m_lpsRegPath(nullptr), m_hkPrimaryHKey(0)
 {
     SetPrimaryKey(hNewPrKey);
     if (SetRegPath(lpzNewRegPath) == FALSE)
@@ -40,12 +40,12 @@ BOOL UsbDkRegAccess::SetRegPath(LPCTSTR lpzNewRegPath)
 
     if (!lpzNewRegPath)
     {
-        m_lpsRegPath = NULL;
+        m_lpsRegPath = nullptr;
         return TRUE;
     }
 
     m_lpsRegPath = _tcsdup(lpzNewRegPath);
-    return (m_lpsRegPath != NULL)?TRUE:FALSE;
+    return (m_lpsRegPath != nullptr)?TRUE:FALSE;
 }
 
 HKEY UsbDkRegAccess::GetPrimaryKey(VOID)
@@ -86,7 +86,7 @@ BOOL UsbDkRegAccess::ReadDWord(LPCTSTR lpzValueName,
     DWORD dwValue = 0,
           dwSize = sizeof(dwValue),
           dwType = REG_DWORD;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -99,7 +99,7 @@ BOOL UsbDkRegAccess::ReadDWord(LPCTSTR lpzValueName,
     {
         if (RegQueryValueEx(hkReadKeyHandle,
                             lpzValueName,
-                            NULL,
+                            nullptr,
                             &dwType,
                             (LPBYTE)&dwValue,
                             &dwSize) == ERROR_SUCCESS)
@@ -124,7 +124,7 @@ DWORD UsbDkRegAccess::ReadString(LPCTSTR lpzValueName,
 {
     DWORD dwRes = 0;
     DWORD dwType = REG_SZ;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwBuffSize = dwNumberOfElements * sizeof(lpzData[0]);
 
@@ -140,7 +140,7 @@ DWORD UsbDkRegAccess::ReadString(LPCTSTR lpzValueName,
     {
         if (RegQueryValueEx(hkReadKeyHandle,
                             lpzValueName,
-                            NULL,
+                            nullptr,
                             &dwType,
                             (LPBYTE)lpzData,
                             &dwBuffSize) == ERROR_SUCCESS)
@@ -161,7 +161,7 @@ LONG UsbDkRegAccess::ReadMultiString(LPCTSTR lpzValueName,
 {
     dwRes = 0;
     DWORD dwType = REG_MULTI_SZ;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwBuffSize = dwNumberOfElements * sizeof(lpzData[0]);
 
@@ -176,7 +176,7 @@ LONG UsbDkRegAccess::ReadMultiString(LPCTSTR lpzValueName,
 
     if (errorCode == ERROR_SUCCESS)
     {
-        errorCode = RegQueryValueEx(hkReadKeyHandle, lpzValueName, NULL, &dwType, (LPBYTE)lpzData, &dwBuffSize);
+        errorCode = RegQueryValueEx(hkReadKeyHandle, lpzValueName, nullptr, &dwType, (LPBYTE)lpzData, &dwBuffSize);
 
         if (errorCode == ERROR_SUCCESS)
         {
@@ -197,7 +197,7 @@ DWORD UsbDkRegAccess::ReadBinary(LPCTSTR lpzValueName,
 {
     DWORD dwRes = 0;
     DWORD dwType = REG_BINARY;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     memset(lpzData, 0, dwSize);
@@ -212,7 +212,7 @@ DWORD UsbDkRegAccess::ReadBinary(LPCTSTR lpzValueName,
     {
         if (RegQueryValueEx(hkReadKeyHandle,
                             lpzValueName,
-                            NULL,
+                            nullptr,
                             &dwType,
                             lpzData,
                             &dwSize) == ERROR_SUCCESS)
@@ -233,7 +233,7 @@ BOOL UsbDkRegAccess::ReadValueName(LPTSTR  lpsValueName,
     BYTE baData[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDataSize = DEFAULT_REG_ENTRY_DATA_LEN,
           dwType = REG_BINARY;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -249,7 +249,7 @@ BOOL UsbDkRegAccess::ReadValueName(LPTSTR  lpsValueName,
                          dwIndex,
                          lpsValueName,
                          &dwBuffSize,
-                         NULL,
+                         nullptr,
                          &dwType,
                          baData,
                          &dwDataSize) == ERROR_SUCCESS)
@@ -266,7 +266,7 @@ BOOL UsbDkRegAccess::ReadKeyName(LPTSTR  lpsKeyName,
                                LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     FILETIME stTimeFile;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
@@ -283,9 +283,9 @@ BOOL UsbDkRegAccess::ReadKeyName(LPTSTR  lpsKeyName,
                          dwIndex,
                          lpsKeyName,
                          &dwBuffSize,
-                         NULL,
-                         NULL,
-                         NULL,
+                         nullptr,
+                         nullptr,
+                         nullptr,
                          &stTimeFile) == ERROR_SUCCESS)
             bResult = TRUE;
         RegCloseKey(hkReadKeyHandle);
@@ -299,7 +299,7 @@ BOOL UsbDkRegAccess::WriteValue(LPCTSTR lpzValueName,
                               LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkWriteKeyHandle = NULL;
+    HKEY hkWriteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDisposition;
 
@@ -311,7 +311,7 @@ BOOL UsbDkRegAccess::WriteValue(LPCTSTR lpzValueName,
                        TEXT(""),
                        REG_OPTION_NON_VOLATILE,
                        KEY_WRITE,
-                       NULL,
+                       nullptr,
                        &hkWriteKeyHandle,
                        &dwDisposition) == ERROR_SUCCESS)
     {
@@ -333,7 +333,7 @@ BOOL UsbDkRegAccess::WriteString(LPCTSTR lpzValueName,
                                LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkWriteKeyHandle = NULL;
+    HKEY hkWriteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDisposition;
 
@@ -345,7 +345,7 @@ BOOL UsbDkRegAccess::WriteString(LPCTSTR lpzValueName,
                        TEXT(""),
                        REG_OPTION_NON_VOLATILE,
                        KEY_WRITE,
-                       NULL,
+                       nullptr,
                        &hkWriteKeyHandle,
                        &dwDisposition) == ERROR_SUCCESS)
     {
@@ -370,7 +370,7 @@ BOOL UsbDkRegAccess::WriteMultiString(LPCTSTR lpzValueName,
                                       LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkWriteKeyHandle = NULL;
+    HKEY hkWriteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDisposition;
 
@@ -382,7 +382,7 @@ BOOL UsbDkRegAccess::WriteMultiString(LPCTSTR lpzValueName,
         TEXT(""),
         REG_OPTION_NON_VOLATILE,
         KEY_WRITE,
-        NULL,
+        nullptr,
         &hkWriteKeyHandle,
         &dwDisposition) == ERROR_SUCCESS)
     {
@@ -408,7 +408,7 @@ BOOL UsbDkRegAccess::WriteBinary(LPCTSTR lpzValueName,
                                LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkWriteKeyHandle = NULL;
+    HKEY hkWriteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDisposition;
 
@@ -420,7 +420,7 @@ BOOL UsbDkRegAccess::WriteBinary(LPCTSTR lpzValueName,
                        TEXT(""),
                        REG_OPTION_NON_VOLATILE,
                        KEY_WRITE,
-                       NULL,
+                       nullptr,
                        &hkWriteKeyHandle,
                        &dwDisposition) == ERROR_SUCCESS)
     {
@@ -440,7 +440,7 @@ BOOL UsbDkRegAccess::WriteBinary(LPCTSTR lpzValueName,
 BOOL UsbDkRegAccess::AddKey(LPCTSTR lpzKeyName)
 {
     BOOL bResult = FALSE;
-    HKEY hkWriteKeyHandle = NULL;
+    HKEY hkWriteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
     DWORD dwDisposition;
 
@@ -452,7 +452,7 @@ BOOL UsbDkRegAccess::AddKey(LPCTSTR lpzKeyName)
                        TEXT(""),
                        REG_OPTION_NON_VOLATILE,
                        KEY_WRITE,
-                       NULL,
+                       nullptr,
                        &hkWriteKeyHandle,
                        &dwDisposition) == ERROR_SUCCESS)
     {
@@ -465,7 +465,7 @@ BOOL UsbDkRegAccess::AddKey(LPCTSTR lpzKeyName)
 BOOL UsbDkRegAccess::DeleteKey(LPCTSTR lpzKeyName, LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkDeleteKeyHandle = NULL;
+    HKEY hkDeleteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -489,7 +489,7 @@ BOOL UsbDkRegAccess::DeleteKey(LPCTSTR lpzKeyName, LPCTSTR lpzSubKey)
 BOOL UsbDkRegAccess::DeleteValue(LPCTSTR lpzValueName, LPCTSTR lpzSubKey)
 {
     BOOL bResult = FALSE;
-    HKEY hkDeleteKeyHandle = NULL;
+    HKEY hkDeleteKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -515,7 +515,7 @@ BOOL UsbDkRegAccess::GetValueInfo(LPCTSTR lpzValueName,
                           LPCTSTR lpzSubKey)
 {
     BOOL bRet = FALSE;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -528,9 +528,9 @@ BOOL UsbDkRegAccess::GetValueInfo(LPCTSTR lpzValueName,
     {
         if (RegQueryValueEx(hkReadKeyHandle,
                             lpzValueName,
-                            NULL,
+                            nullptr,
                             lpDataType,
-                            NULL,
+                            nullptr,
                             lpDataSize) == ERROR_SUCCESS)
             bRet = TRUE;
 
@@ -548,7 +548,7 @@ BOOL UsbDkRegAccess::GetKeyInfo(LPDWORD lpdwNofSubKeys,
                               LPCTSTR lpzSubKey)
 {
     BOOL bRet = FALSE;
-    HKEY hkReadKeyHandle = NULL;
+    HKEY hkReadKeyHandle = nullptr;
     TCHAR tcaFullRegPath[DEFAULT_REG_ENTRY_DATA_LEN];
 
     FormatFullRegPath(tcaFullRegPath, TBUF_SIZEOF(tcaFullRegPath), lpzSubKey);
@@ -560,17 +560,17 @@ BOOL UsbDkRegAccess::GetKeyInfo(LPDWORD lpdwNofSubKeys,
                      &hkReadKeyHandle) == ERROR_SUCCESS)
     {
         if (RegQueryInfoKey(hkReadKeyHandle,
-                            NULL,
-                            NULL,
-                            NULL,
+                            nullptr,
+                            nullptr,
+                            nullptr,
                             lpdwNofSubKeys,
                             lpdwMaxSubKeyLen,
-                            NULL,
+                            nullptr,
                             lpdwNofValues,
                             lpdwMaxValueNameLen,
                             lpdwMaxValueLen,
-                            NULL,
-                            NULL) == ERROR_SUCCESS)
+                            nullptr,
+                            nullptr) == ERROR_SUCCESS)
             bRet = TRUE;
 
         RegCloseKey(hkReadKeyHandle);
diff --git a/UsbDkHelper/RegAccess.h b/UsbDkHelper/RegAccess.h
index df1d29e..556eb2c 100644
--- a/UsbDkHelper/RegAccess.h
+++ b/UsbDkHelper/RegAccess.h
@@ -30,60 +30,60 @@ public:
     BOOL  ReadValueName(LPTSTR lpsValueName,
                         DWORD  dwNumberOfElements,
                         DWORD  dwIndex=0,
-                        LPCTSTR lpzSubKey=NULL);
+                        LPCTSTR lpzSubKey=nullptr);
     BOOL  ReadKeyName(LPTSTR  lpsKeyName,
                       DWORD   dwNumberOfElements,
                       DWORD   dwIndex,
-                      LPCTSTR lpzSubKey = NULL);
+                      LPCTSTR lpzSubKey = nullptr);
 
     BOOL GetValueInfo(LPCTSTR lpzValueName,
                       DWORD*  lpDataType,
                       DWORD*  lpDataSize,
-                      LPCTSTR lpzSubKey = NULL);
+                      LPCTSTR lpzSubKey = nullptr);
     BOOL GetKeyInfo(LPDWORD lpdwNofSubKeys,
                     LPDWORD lpdwMaxSubKeyLen,
                     LPDWORD lpdwNofValues,
                     LPDWORD lpdwMaxValueNameLen,
                     LPDWORD lpdwMaxValueLen,
-                    LPCTSTR lpzSubKey = NULL);
+                    LPCTSTR lpzSubKey = nullptr);
 
     DWORD ReadDWord(LPCTSTR lpzValueName,
                     DWORD   dwDefault = 0,
-                    LPCTSTR lpzSubKey = NULL);
+                    LPCTSTR lpzSubKey = nullptr);
     BOOL  ReadDWord(LPCTSTR lpzValueName,
                     LPDWORD lpdwValue,
-                    LPCTSTR lpzSubKey = NULL);
+                    LPCTSTR lpzSubKey = nullptr);
     DWORD ReadString(LPCTSTR lpzValueName,
                      LPTSTR  lpzData,
                      DWORD   dwNumberOfElements,
-                     LPCTSTR lpzSubKey=NULL);
+                     LPCTSTR lpzSubKey=nullptr);
     LONG ReadMultiString(LPCTSTR lpzValueName,
                           LPTSTR  lpzData,
                           DWORD   dwNumberOfElements,
                           DWORD   &dwRes,
-                          LPCTSTR lpzSubKey = NULL);
+                          LPCTSTR lpzSubKey = nullptr);
     DWORD ReadBinary(LPCTSTR lpzValueName,
                      LPBYTE  lpzData,
                      DWORD   dwSize,
-                     LPCTSTR lpzSubKey=NULL);
+                     LPCTSTR lpzSubKey=nullptr);
     BOOL  WriteValue(LPCTSTR lpzValueName,
                      DWORD  dwValue,
-                     LPCTSTR lpzSubKey = NULL);
+                     LPCTSTR lpzSubKey = nullptr);
     BOOL  WriteString(LPCTSTR lpzValueName,
                       LPCTSTR lpzValue,
-                      LPCTSTR lpzSubKey=NULL);
+                      LPCTSTR lpzSubKey=nullptr);
     BOOL  WriteMultiString(LPCTSTR lpzValueName,
                            LPCTSTR lpzValue,
                            DWORD dwBuffSize,
-                           LPCTSTR lpzSubKey = NULL);
+                           LPCTSTR lpzSubKey = nullptr);
     BOOL  WriteBinary(LPCTSTR lpzValueName,
                       LPCBYTE lpData,
                       DWORD   dwDataSize,
-                      LPCTSTR lpzSubKey = NULL);
+                      LPCTSTR lpzSubKey = nullptr);
     BOOL  DeleteKey(LPCTSTR lpzKeyName,
-                    LPCTSTR lpzSubKey = NULL);
+                    LPCTSTR lpzSubKey = nullptr);
     BOOL  DeleteValue(LPCTSTR lpzValueName,
-                      LPCTSTR lpzSubKey = NULL);
+                      LPCTSTR lpzSubKey = nullptr);
 
     BOOL  AddKey(LPCTSTR lpzKeyName);
 
diff --git a/UsbDkHelper/ServiceManager.cpp b/UsbDkHelper/ServiceManager.cpp
index 29fb532..c68a22e 100644
--- a/UsbDkHelper/ServiceManager.cpp
+++ b/UsbDkHelper/ServiceManager.cpp
@@ -5,7 +5,7 @@
 
 ServiceManager::ServiceManager()
 {
-    m_schSCManager = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS);
+    m_schSCManager = OpenSCManager(nullptr, nullptr, SC_MANAGER_ALL_ACCESS);
 
     if (!m_schSCManager)
     {
@@ -16,7 +16,7 @@ ServiceManager::ServiceManager()
 
 ServiceManager::~ServiceManager()
 {
-    assert(NULL != m_schSCManager);
+    assert(nullptr != m_schSCManager);
 
     CloseServiceHandle(m_schSCManager);
 }
@@ -24,12 +24,12 @@ ServiceManager::~ServiceManager()
 
 void ServiceManager::CreateServiceObject(const tstring &ServiceName, const tstring &ServicePath)
 {
-    assert(NULL != m_schSCManager);
+    assert(nullptr != m_schSCManager);
 
     auto schService = CreateService(m_schSCManager, ServiceName.c_str(), ServiceName.c_str(), SERVICE_ALL_ACCESS, SERVICE_KERNEL_DRIVER,
-                                SERVICE_DEMAND_START, SERVICE_ERROR_NORMAL, ServicePath.c_str(), NULL, NULL,    NULL, NULL,    NULL);
+                                SERVICE_DEMAND_START, SERVICE_ERROR_NORMAL, ServicePath.c_str(), nullptr, nullptr,    nullptr, nullptr,    nullptr);
 
-    if (NULL == schService)
+    if (nullptr == schService)
     {
         throw UsbDkServiceManagerFailedException(TEXT("CreateService failed"));
     }
@@ -40,10 +40,10 @@ void ServiceManager::CreateServiceObject(const tstring &ServiceName, const tstri
 
 void ServiceManager::DeleteServiceObject(const tstring &ServiceName)
 {
-    assert(NULL != m_schSCManager);
+    assert(nullptr != m_schSCManager);
 
     auto schService = OpenService(m_schSCManager, ServiceName.c_str(), SERVICE_ALL_ACCESS);
-    if (NULL == schService)
+    if (nullptr == schService)
     {
         auto  err = GetLastError();
         if (err != ERROR_SERVICE_DOES_NOT_EXIST)
diff --git a/UsbDkHelper/WdfCoinstaller.cpp b/UsbDkHelper/WdfCoinstaller.cpp
index 83c2001..2489b10 100644
--- a/UsbDkHelper/WdfCoinstaller.cpp
+++ b/UsbDkHelper/WdfCoinstaller.cpp
@@ -36,7 +36,7 @@ void WdfCoinstaller::loadWdfCoinstaller()
 
     m_wdfCoinstallerLibrary = LoadLibrary(coinstallerFullPath.str().c_str());
 
-    if (NULL == m_wdfCoinstallerLibrary)
+    if (nullptr == m_wdfCoinstallerLibrary)
     {
         throw UsbDkWdfCoinstallerFailedException(tstring(TEXT("LoadLibrary(")) + currDir + TEXT(") failed"));
     }
@@ -114,7 +114,7 @@ void WdfCoinstaller::freeWdfCoinstallerLibrary()
     if (m_wdfCoinstallerLibrary)
     {
         FreeLibrary(m_wdfCoinstallerLibrary);
-        m_wdfCoinstallerLibrary = NULL;
+        m_wdfCoinstallerLibrary = nullptr;
     }
 }
 //--------------------------------------------------------------------------------
diff --git a/UsbDkHelper/WdfCoinstaller.h b/UsbDkHelper/WdfCoinstaller.h
index 1b80eb3..1ad456e 100644
--- a/UsbDkHelper/WdfCoinstaller.h
+++ b/UsbDkHelper/WdfCoinstaller.h
@@ -40,7 +40,7 @@ private:
     CallbackType getCoinstallerFunction(char *functionName)
     {
         auto ptfFunction = (CallbackType)GetProcAddress(m_wdfCoinstallerLibrary, functionName);
-        if (ptfFunction == NULL)
+        if (ptfFunction == nullptr)
         {
             throw UsbDkWdfCoinstallerFailedException(L"WdfCoinstaller throw the exception. GetProcAddress failed!");
         }
diff --git a/UsbDkHelper/tstrings.cpp b/UsbDkHelper/tstrings.cpp
index 93a54e0..bf37017 100644
--- a/UsbDkHelper/tstrings.cpp
+++ b/UsbDkHelper/tstrings.cpp
@@ -8,7 +8,7 @@ string __wstring2string(const wstring& str)
    char* buf = new (std::nothrow) char[buf_length];
    size_t nCount;
 
-   if(NULL == buf)
+   if(nullptr == buf)
    {
        return string();
    }
@@ -29,7 +29,7 @@ wstring __string2wstring(const string& str)
     wchar_t* buf = new (std::nothrow) wchar_t[buf_length];
     size_t nCount;
 
-    if(NULL == buf)
+    if(nullptr == buf)
     {
         return wstring();
     }