diff --git a/exe/diversipub b/exe/diversipub
index 3ba7ada..b680bba 100755
--- a/exe/diversipub
+++ b/exe/diversipub
@@ -12,6 +12,9 @@ rescue LoadError
   require gem_name
 end
 
+$stdout.sync = true
+$stderr.sync = true
+
 main = Diversipub::Main.new(
   program_name: $PROGRAM_NAME,
   argv: ARGV,