diff --git a/py/program.py b/py/program.py
index 29e31bc..51a6475 100755
--- a/py/program.py
+++ b/py/program.py
@@ -203,6 +203,7 @@
 
 def PrintStderr(msg, trailing="\n"):
     sys.stderr.write(msg + trailing)
+    sys.stderr.flush()
 
 # End of 'PrintStderr()'
 
@@ -213,6 +214,7 @@
 
 def PrintStdout(msg, trailing="\n"):
     sys.stdout.write(msg + trailing)
+    sys.stdout.flush()
 
 # End of 'PrintStdout'