Hi Daniel, I know your question is already 4 months old, but maybe its still useful for you. I think you forgot to add -D_WIN32_WINNT=0x0600 to the g++ command line. I can still compile with mingw_w64, even though I dont recommend it because support for it was dropped by the seqan team :) PS: this commandline works for my simple testproject g++ -I ..\..\seqan\include -DWIN32 -D_WINDOWS -D_WIN32_WINNT=0x0600 testprojekt.cpp -o testprojekt_mingw.exe Best Regards, Benjamin