diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 071cfb07bf..9782fffa2d 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -511,6 +511,7 @@ class Formula
 
     log = File.open(logfn, "w")
     log.puts Time.now, "", cmd, args, ""
+    log.flush
 
     if verbose
       rd, wr = IO.pipe