diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -421,6 +421,9 @@
         options.color = False
     else: # 'always', for testing purposes
         options.color = pygmentspresent
+        if not pygmentspresent:
+            sys.stderr.write('warning: --color=always ignored because'
+                             'pygments is not installed\n')
 
     global useipv6
     if options.ipv6: