Possible overflow when using QtConcurrent package on x64

When using QtConcurrent mapping methods on x64 architectures, a warning is issued during build.

This comes from the integer member iterationCount of IterateKernel template class. std::distance is used to init this variable. This method returns an architecture dependent type (size of pointer). Thus, on x64 architectures, std::distance returns an int64. However, iterationCount is only an int. This may truncate the value of std::distance.

With Qt 4.8.5, the warning is visible only when qt has been built with STL support (i.e. QT_NO_STL is not defined).
From Qt 5, it seems that the warning should happen everytime.

It does not seem harmful, but in some cases, it could...

What would you recommend to do about this?