diff --git a/tools/python/jwutils/log.py b/tools/python/jwutils/log.py
index 590af6d..df40cd2 100644
--- a/tools/python/jwutils/log.py
+++ b/tools/python/jwutils/log.py
@@ -116,7 +116,7 @@ def slog(prio, *args, **kwargs): # export
         msg += misc.pad(name, _file_name_len) + '[' + misc.pad(str(line), 4, True) + ']'
 
     if f_color in _flags:
-        color_on, color_off = _prio_colors[prio]
+        color_on, color_off = console_color_chars(prio)
 
     msg += _log_prefix
 
@@ -174,8 +174,10 @@ def parse_log_prio_str(prio): # export
             return map_prio_str_to_val[prio]
     raise Exception("Unknown priority string \"", prio, "\"")
 
-def prio_colors(prio): # export
-    return _prio_colors(prio)
+def console_color_chars(prio): # export
+    if not sys.stdout.isatty():
+        return [ '', '' ]
+    return _prio_colors[prio]
 
 def set_level(level_): # export
     global _level
@@ -222,6 +224,3 @@ def set_filename_length(l): # export
     if l:
         _file_name_len = l
     return r
-
-def console_color_chars(prio): # export
-    return _prio_colors[prio]