diff --git a/Library/Homebrew/build.rb b/Library/Homebrew/build.rb
index e75a6841ef..693b129d4f 100755
--- a/Library/Homebrew/build.rb
+++ b/Library/Homebrew/build.rb
@@ -46,6 +46,7 @@ def main
 rescue Exception => e
   unless error_pipe.nil?
     e.continuation = nil if ARGV.debug?
+    error_pipe.flush
     Marshal.dump(e, error_pipe)
     error_pipe.close
     exit! 1
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index c0348fe51a..5612815e5c 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -371,6 +371,7 @@ class FormulaInstaller
         read.close
         exec(*args)
       rescue Exception => e
+        write.flush
         Marshal.dump(e, write)
         write.close
         exit! 1
@@ -378,6 +379,7 @@ class FormulaInstaller
     end
 
     ignore_interrupts(:quietly) do # the fork will receive the interrupt and marshall it back
+      write.flush
       write.close
       Process.wait
       data = read.read