diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 75a9bec02ea..f01dcef308a 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -540,6 +540,8 @@ def main(tests=None, testdir=None, verbose=0, quiet=False,
                     print stdout
                 if stderr:
                     print >>sys.stderr, stderr
+                sys.stdout.flush()
+                sys.stderr.flush()
                 if result[0] == INTERRUPTED:
                     assert result[1] == 'KeyboardInterrupt'
                     raise KeyboardInterrupt   # What else?