diff --git a/configure.ac b/configure.ac
index 1de852d7..5ac46956 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,7 +39,7 @@ case "$host_os" in
      AC_DEFINE_UNQUOTED(CYGWIN,1,[This is a Cygwin system])
      AC_DEFINE_UNQUOTED(WINDOWS,1,[This is a Windows system])
      ;;
-*mingw*)
+*mingw* | *msys*)
      AC_DEFINE_UNQUOTED(MINGW,1,[This is a MinGW system])
      AC_DEFINE_UNQUOTED(WINDOWS,1,[This is a Windows system])
      AC_CHECK_HEADER(winsock2.h, , [AC_MSG_ERROR([** MinGW and no winsock2.h.  I give up.])])