Calling VS 2013 dll from VS 2008 dll

I am planning to call (functions in) VS2013 compiled dll from VS2008 compiled. I am worried that this may fail (because dll format of VS2013 may not be known to the older runtime) . Both the exe and the dll are unmanaged C++ . My functions arguments only involve int, double , or char * . Is my apprehension unfounded? Are dll formats standard enough ( for these simple cases ) that it is (almost ) guaranteed to work. Note: I am talking about dynamically loaded dlls( no static linking is involved)