diff --git a/sphinx/__init__.py b/sphinx/__init__.py
index 57811b452b..96057951ba 100644
--- a/sphinx/__init__.py
+++ b/sphinx/__init__.py
@@ -99,7 +99,7 @@ def main(argv):
         elif opt == '-N':
             nocolor()
 
-    if sys.platform == 'win32':
+    if not sys.stdout.isatty() or sys.platform == 'win32':
         # Windows' cmd box doesn't understand ANSI sequences
         nocolor()