<DIV> </DIV> <DIV>I'm not clear as to what you are building - you refer to DLL's, but the build command that you have given is not for a dll, it's for a static library.</DIV> <DIV> </DIV> <DIV>The message "The app could not be initialised" usually indicates that the Win32 EXE file is either corrupt or has been linked incorrectly. There are various tools that can examine the contents and structure of Win PE's (portable executable files, ie exe's and dll's).</DIV> <DIV> </DIV> <DIV>Regarding gcc 3.4.2, I read at the gmp home page that this version of gcc was not regarded  as being reliable, and it recommended building gmp with gcc 3.3.x.</DIV> <DIV> </DIV> <DIV>So when I built my Win DLL for GMP 4.1.4,  I didn't even try with gcc 3.4.2, I got a gcc 3.3.2 version and used that, and had no problems with that, using MinGw/MSys 1.0.10</DIV> <DIV> </DIV> <DIV>Unless you have a special reason for wanting a static library, perhaps you might try doing a shared build (--disable-static --enable-shared) instead - see if you that works - dll problems are easier to identify than static lib problems.</DIV> <DIV> </DIV> <DIV> </DIV> <DIV>Jim White</DIV> <DIV><BR> </DIV>