diff --git a/librb/configure.ac b/librb/configure.ac
index 0e434c93..127214d3 100644
--- a/librb/configure.ac
+++ b/librb/configure.ac
@@ -62,8 +62,7 @@ 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*)
-*msys*)
+*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(windows.h, , [AC_MSG_ERROR([** MinGW and no windows.h.  I give up.])])