--- a/testing/mozbase/mozinfo/mozinfo/mozinfo.py
+++ b/testing/mozbase/mozinfo/mozinfo/mozinfo.py
@@ -82,17 +82,17 @@ if system in ["Microsoft", "Windows"]:
         # On windows >= 8.1 the system call that getwindowsversion uses has
         # been frozen to always return the same values. In this case we call
         # the RtlGetVersion API directly, which still provides meaningful
         # values, at least for now.
         major, minor, build_number = get_windows_version()
         version = "%d.%d.%d" % (major, minor, build_number)
 
     os_version = "%d.%d" % (major, minor)
-elif system.startswith('MINGW'):
+elif system.startswith(('MINGW', 'MSYS_NT')):
     # windows/mingw python build (msys)
     info['os'] = 'win'
     os_version = version = unknown
 elif system == "Linux":
     if hasattr(platform, "linux_distribution"):
         (distro, os_version, codename) = platform.linux_distribution()
     else:
         (distro, os_version, codename) = platform.dist()