Warning C4267 'initializing': conversion from 'size_t' to 'DWORD', possible loss of data

I am getting the below warning message when compiling my C++ application,

Warning C4267 'initializing': conversion from 'size_t' to 'DWORD', possible loss of data at the below line:

DWORD nPos = strRegPath.find(REG_SOFTWARE); 

Below is my complete code:

Declaration:

#define REG_SOFTWARE L"Software"
wchar_t* m_wszParams;

Definition:

wstring strRegPath = m_wszParams;

DWORD nPos = strRegPath.find(REG_SOFTWARE); 

Could anyone please help me how to resolve this warning?

Thanks in advance.