diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index a76740ef7c..f68df9d74e 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -552,7 +552,7 @@ protected
   rescue ErrorDuringExecution => e
     raise BuildError.new(self, cmd, args, $?)
   ensure
-    f.close if f
+    f.close if f and not f.closed?
     removed_ENV_variables.each do |key, value|
       ENV[key] = value
     end if removed_ENV_variables