diff --git a/lib/pyulib/src/ulib/base/output.py b/lib/pyulib/src/ulib/base/output.py
index ebb4ee6..4eed0cf 100644
--- a/lib/pyulib/src/ulib/base/output.py
+++ b/lib/pyulib/src/ulib/base/output.py
@@ -40,7 +40,7 @@ OUT_ISATTY = _isatty(OUT)
 ERR = sys.stderr
 ERR_ISATTY = _isatty(ERR)
 
-USE_COLORS = OUT_ISATTY and ERR_ISATTY
+USE_COLORS = OUT_ISATTY and ERR_ISATTY and not os.environ.get('UTOOLS_NO_COLORS', '')
 RESET = '0'
 BLACK = '30'; RED = '31'; GREEN = '32'; YELLOW = '33'
 BLUE = '34'; MAGENTA = '35'; CYAN = '36'; WHITE = '37'