Even  though building didn't seem to max out my memory usage, I tried shutting everything unnecessary down and making again. The make seemed to succeed but make-check failed all test: make[4]: Entering directory `/c/assembler/gmp- 4.2.2/tests' FAIL: t-bswap.exe FAIL: t-constants.exe FAIL: t-count_zeros.exe FAIL: t-gmpmax.exe FAIL: t-hightomask.exe FAIL: t-modlinv.exe FAIL: t-popc.exe FAIL: t-parity.exe FAIL: t-sub.exe ================================== 9 of 9 tests failed I have a suspicion that the tests can't find the DLL.  I can't find the DLL.  Maybe I did something something wrong with that "--prefix"  option that I don't understand.  I created a directory "c:/assember/gmpinstall" and my configure line was "./configure --build=i368-pc-mingw32 --enable-fat -prefix=c:/assembler/gmpinstall --disable-static --enable-shared" Anyway that directory is empty and a search of the entire disk didn't turn up a gmp.dll Odd that that the make seemed to succeed. Joshua Scholar