diff --git a/xmlrunner/result.py b/xmlrunner/result.py
index 9b60988..d8f3905 100644
--- a/xmlrunner/result.py
+++ b/xmlrunner/result.py
@@ -175,6 +175,7 @@ def callback():
                 )
             elif self.dots:
                 self.stream.write(short_str)
+            self.stream.flush()
         self.callback = callback
 
     def startTest(self, test):