diff --git a/lib/lrama/output.rb b/lib/lrama/output.rb
index eaefbd04..696aa79f 100644
--- a/lib/lrama/output.rb
+++ b/lib/lrama/output.rb
@@ -53,9 +53,7 @@ def render
           if @header_out
             @header_out << tmp
           else
-            File.open(@header_file_path, "w+") do |f|
-              f << tmp
-            end
+            File.write(@header_file_path, tmp)
           end
         end
       end
diff --git a/spec/lrama/output_spec.rb b/spec/lrama/output_spec.rb
index 90b84506..4afae322 100644
--- a/spec/lrama/output_spec.rb
+++ b/spec/lrama/output_spec.rb
@@ -10,7 +10,7 @@
       header_out: header_out,
       header_file_path: "y.tab.h",
       context: context,
-      grammar: grammar,      
+      grammar: grammar,
     )
   }
   let(:out) { StringIO.new }