libwinpthread-1.dll dependency

Hi, I work with a qt 4.8.5 compiled statically on W7, I try now to remove all dependencies of my .exe. First the last dll needed was libgcc_s_sjlj-1.dll, libstdc++-6.dll and libwinpthread-1.dll So I added the following lines in my .pro QMAKE_LFLAGS += -static-libgcc QMAKE_LFLAGS = -static-libstdc+ But the .exe still needs libwinpthread-1.dll, what do i need to add in my .pro to remove this dependency ? Thanks