diff --git a/README.md b/README.md
index f42b95e6..87f81d08 100644
--- a/README.md
+++ b/README.md
@@ -36,13 +36,8 @@ $ lrama -d sample/parse.y
 ```
 
 ```shell
-# "y.tab.c" and "y.tab.h" are generated and added `#include "y.tab.h"`
-$ lrama -d sample/parse.y --auto-include
-```
-
-```shell
-# "calc", "calc.c", and "calc.h" are generated and added `#include "calc.h"`
-$ lrama -d sample/calc.y -o calc.c --auto-include && gcc -Wall calc.c -o calc && ./calc
+# "calc", "calc.c", and "calc.h" are generated
+$ lrama -d sample/calc.y -o calc.c && gcc -Wall calc.c -o calc && ./calc
 Enter the formula:
 1
 => 1
diff --git a/lib/lrama/command.rb b/lib/lrama/command.rb
index 301b3e67..213b7acb 100644
--- a/lib/lrama/command.rb
+++ b/lib/lrama/command.rb
@@ -8,7 +8,7 @@ def run(argv)
       warning = Lrama::Warning.new
       text = options.y.read
       options.y.close if options.y != STDIN
-      grammar = Lrama::NewParser.new(text, options.include_header).parse
+      grammar = Lrama::NewParser.new(text).parse
       states = Lrama::States.new(grammar, warning, trace_state: (options.trace_opts[:automaton] || options.trace_opts[:closure]))
       states.compute
       context = Lrama::Context.new(states)
diff --git a/lib/lrama/new_parser.rb b/lib/lrama/new_parser.rb
index ea819939..a33fdfdc 100644
--- a/lib/lrama/new_parser.rb
+++ b/lib/lrama/new_parser.rb
@@ -670,9 +670,8 @@ class NewParser < Racc::Parser
 
 module_eval(<<'...end parser.y/module_eval...', 'parser.y', 378)
 
-def initialize(text, include_header)
+def initialize(text)
   @text = text
-  @include_header = include_header
 end
 
 def parse
@@ -690,14 +689,6 @@ def parse
 def next_token
   @lexer.next_token
 end
-
-def prologue(s_value)
-  if @include_header && !s_value.match?(/^\s*#include\s+"#{@include_header}"/)
-    "\n#include \"#{@include_header}\"\n" + s_value
-  else
-    s_value
-  end
-end
 ...end parser.y/module_eval...
 ##### State transition tables begin ###
 
@@ -1127,7 +1118,7 @@ def _reduce_5(val, _values, result)
 
 module_eval(<<'.,.,', 'parser.y', 20)
   def _reduce_6(val, _values, result)
-                                @grammar.prologue = prologue(val[2].s_value)
+                                @grammar.prologue = val[2].s_value
 
     result
   end
diff --git a/lib/lrama/option_parser.rb b/lib/lrama/option_parser.rb
index c33c0aa7..35725fc6 100644
--- a/lib/lrama/option_parser.rb
+++ b/lib/lrama/option_parser.rb
@@ -39,10 +39,6 @@ def parse(argv)
         end
       end
 
-      if @options.auto_include
-        @options.include_header = @options.header_file.sub("./", "")
-      end
-
       @options
     end
 
@@ -66,7 +62,6 @@ def parse_by_option_parser(argv)
         o.separator 'Output:'
         o.on('-h', '--header=[FILE]', 'also produce a header file named FILE') {|v| @options.header = true; @options.header_file = v }
         o.on('-d', 'also produce a header file') { @options.header = true }
-        o.on('--auto-include', 'also include header files automatically') {|v| @options.auto_include = true }
         o.on('-r', '--report=THINGS', Array, 'also produce details on the automaton') {|v| @report = v }
         o.on('--report-file=FILE', 'also produce details on the automaton output to a file named FILE') {|v| @options.report_file = v }
         o.on('-o', '--output=FILE', 'leave output to FILE') {|v| @options.outfile = v }
diff --git a/lib/lrama/options.rb b/lib/lrama/options.rb
index 0fed96e5..01b3e701 100644
--- a/lib/lrama/options.rb
+++ b/lib/lrama/options.rb
@@ -1,8 +1,8 @@
 module Lrama
   # Command line options.
   class Options
-    attr_accessor :skeleton, :header, :header_file, :auto_include,
-                  :include_header, :report_file, :outfile,
+    attr_accessor :skeleton, :header, :header_file,
+                  :report_file, :outfile,
                   :error_recovery, :grammar_file,
                   :report_file, :trace_opts, :report_opts, :y
 
@@ -10,8 +10,6 @@ def initialize
       @skeleton = "bison/yacc.c"
       @header = false
       @header_file = nil
-      @auto_include = false
-      @include_header = nil
       @report_file = nil
       @outfile = "y.tab.c"
       @error_recovery = false
diff --git a/lib/lrama/output.rb b/lib/lrama/output.rb
index 1a9a84d6..5bc4d1ab 100644
--- a/lib/lrama/output.rb
+++ b/lib/lrama/output.rb
@@ -7,7 +7,7 @@ class Output
     extend Forwardable
     include Report::Duration
 
-    attr_reader :grammar_file_path, :context, :grammar, :error_recovery
+    attr_reader :grammar_file_path, :context, :grammar, :error_recovery, :include_header
 
     def_delegators "@context", :yyfinal, :yylast, :yyntokens, :yynnts, :yynrules, :yynstates,
                                :yymaxutok, :yypact_ninf, :yytable_ninf
@@ -28,6 +28,7 @@ def initialize(
       @context = context
       @grammar = grammar
       @error_recovery = error_recovery
+      @include_header = header_file_path ? header_file_path.sub("./", "") : nil
     end
 
     if ERB.instance_method(:initialize).parameters.last.first == :key
diff --git a/parser.y b/parser.y
index 390248dd..5301eabd 100644
--- a/parser.y
+++ b/parser.y
@@ -18,7 +18,7 @@ rule
                           }
                         "%}"
                           {
-                            @grammar.prologue = prologue(val[2].s_value)
+                            @grammar.prologue = val[2].s_value
                           }
                       | "%require" STRING
 
@@ -376,9 +376,8 @@ end
 
 ---- inner
 
-def initialize(text, include_header)
+def initialize(text)
   @text = text
-  @include_header = include_header
 end
 
 def parse
@@ -397,10 +396,3 @@ def next_token
   @lexer.next_token
 end
 
-def prologue(s_value)
-  if @include_header && !s_value.match?(/^\s*#include\s+"#{@include_header}"/)
-    "\n#include \"#{@include_header}\"\n" + s_value
-  else
-    s_value
-  end
-end
diff --git a/spec/lrama/context_spec.rb b/spec/lrama/context_spec.rb
index 44150088..d81d5964 100644
--- a/spec/lrama/context_spec.rb
+++ b/spec/lrama/context_spec.rb
@@ -5,7 +5,7 @@
   describe "basic" do
     it do
       y = File.read(fixture_path("context/basic.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
       context = Lrama::Context.new(states)
@@ -181,7 +181,7 @@
 %%
         INPUT
 
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
         context = Lrama::Context.new(states)
@@ -230,7 +230,7 @@
 %%
         INPUT
 
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
         context = Lrama::Context.new(states)
diff --git a/spec/lrama/new_parser_spec.rb b/spec/lrama/new_parser_spec.rb
index b9c69b0b..c5ecda4b 100644
--- a/spec/lrama/new_parser_spec.rb
+++ b/spec/lrama/new_parser_spec.rb
@@ -41,7 +41,7 @@
   describe '#parse' do
     it "basic" do
       y = File.read(fixture_path("common/basic.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
 
       expect(grammar.union.code.s_value).to eq(<<-CODE.chomp)
 
@@ -408,7 +408,7 @@
 
     it "nullable" do
       y = File.read(fixture_path("common/nullable.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
 
       expect(grammar.nterms.sort_by(&:number)).to eq([
         Sym.new(id: T.new(type: T::Ident, s_value: "$accept"),       alias_name: nil, number:  6, tag: nil, term: false, token_id: 0, nullable: false),
@@ -562,7 +562,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
 %%
       INPUT
 
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
 
       expect(grammar._rules).to eq([
         [
@@ -605,7 +605,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
 %%
 
       INPUT
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
 
       expect(grammar.terms.sort_by(&:number)).to eq([
         Sym.new(id: T.new(type: T::Ident, s_value: "EOI"),           alias_name: "\"EOI\"",           number:  0, tag: nil,                                   term: true, token_id:   0, nullable: false, precedence: nil),
@@ -661,7 +661,7 @@ class : keyword_class { code 1 } tSTRING { code 2 } keyword_end { code 3 }
 %%
 
       INPUT
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
 
       expect(grammar.nterms.sort_by(&:number)).to eq([
         Sym.new(id: T.new(type: T::Ident, s_value: "$accept"), alias_name: nil, number: 11, tag: nil,                                 term: false, token_id: 0, nullable: false),
@@ -756,7 +756,7 @@ class : keyword_class tSTRING %prec tPLUS keyword_end { code 1 }
 %%
 
         INPUT
-        parser = Lrama::NewParser.new(y, nil)
+        parser = Lrama::NewParser.new(y)
 
         expect { parser.parse }.to raise_error("Ident after %prec")
       end
@@ -773,7 +773,7 @@ class : keyword_class { code 2 } tSTRING %prec "=" '!' keyword_end { code 3 }
 %%
 
         INPUT
-        parser = Lrama::NewParser.new(y, nil)
+        parser = Lrama::NewParser.new(y)
 
         expect { parser.parse }.to raise_error("Char after %prec")
       end
@@ -790,7 +790,7 @@ class : keyword_class { code 4 } tSTRING '?' keyword_end %prec tEQ { code 5 } {
 %%
 
         INPUT
-        parser = Lrama::NewParser.new(y, nil)
+        parser = Lrama::NewParser.new(y)
 
         expect { parser.parse }.to raise_error("Multiple User_code after %prec")
       end
@@ -811,7 +811,7 @@ class : keyword_class
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         codes = grammar.rules.map(&:code).compact
 
         expect(codes.count).to eq(1)
@@ -838,7 +838,7 @@ class : keyword_class
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         codes = grammar.rules.map(&:code).compact
 
         expect(codes.count).to eq(1)
@@ -883,7 +883,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
 %%
 
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
 
         expect(grammar.terms.sort_by(&:number)).to eq([
           Sym.new(id: T.new(type: T::Ident, s_value: "EOI"),           alias_name: "\"EOI\"",           number:  0, tag: nil,                                   term: true, token_id:   0, nullable: false),
@@ -932,7 +932,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
 %%
 
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
 
         expect(grammar.terms.sort_by(&:number)).to eq([
           Sym.new(id: T.new(type: T::Ident, s_value: "EOI"),           alias_name: "\"EOI\"",           number: 0, tag: nil,                                   term: true, token_id:   0, nullable: false, precedence: nil),
@@ -978,7 +978,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
         ;
 %%
           INPUT
-          grammar = Lrama::NewParser.new(y, nil).parse
+          grammar = Lrama::NewParser.new(y).parse
 
           expect(grammar.rules).to eq([
             Rule.new(
@@ -1086,7 +1086,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
    ;
 %%
           INPUT
-          grammar = Lrama::NewParser.new(y, nil).parse
+          grammar = Lrama::NewParser.new(y).parse
 
           expect(grammar.rules).to eq([
             Rule.new(
@@ -1177,7 +1177,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
                 { $$ = $1 - $2; }
 ;
             INPUT
-            grammar = Lrama::NewParser.new(y, nil).parse
+            grammar = Lrama::NewParser.new(y).parse
 
             expect(grammar.rules).to eq([
               Rule.new(
@@ -1311,7 +1311,7 @@ class : keyword_class tSTRING keyword_end { code 1 }
 ;
             INPUT
 
-            expect { Lrama::NewParser.new(y, nil).parse }.to raise_error("'results' is invalid name.")
+            expect { Lrama::NewParser.new(y).parse }.to raise_error("'results' is invalid name.")
           end
         end
       end
@@ -1348,7 +1348,7 @@ class : keyword_class tSTRING keyword_end ;
 
 %%
       INPUT
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       terms = grammar.terms.sort_by(&:number).map do |term|
         [term.id.s_value, term.token_id]
       end
@@ -1397,7 +1397,7 @@ class : keyword_class tSTRING keyword_end
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         codes = grammar.rules.map(&:code)
 
         expect(codes.count).to eq(3)
@@ -1444,7 +1444,7 @@ class : keyword_class tSTRING keyword_end
 %%
         INPUT
 
-        expect { Lrama::NewParser.new(y, nil).parse }.to raise_error(RuntimeError) do |e|
+        expect { Lrama::NewParser.new(y).parse }.to raise_error(RuntimeError) do |e|
           expect(e.message).to eq(<<~MSG.chomp)
             $$ of 'stmt' has no declared type
             $1 of 'stmt' has no declared type
diff --git a/spec/lrama/states_spec.rb b/spec/lrama/states_spec.rb
index 43f910ad..4ac84c38 100644
--- a/spec/lrama/states_spec.rb
+++ b/spec/lrama/states_spec.rb
@@ -5,7 +5,7 @@
   describe '#compute' do
     it "basic" do
       y = File.read(fixture_path("common/basic.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -298,7 +298,7 @@ class    go to state 5
 
     it '#State#accessing_symbol' do
       y = File.read(fixture_path("common/basic.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -338,7 +338,7 @@ class    go to state 5
   describe '#reads_relation' do
     it do
       y = File.read(fixture_path("states/reads_relation.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -605,7 +605,7 @@ class    go to state 5
   describe '#includes_relation' do
     it do
       y = File.read(fixture_path("states/includes_relation.y"))
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -904,7 +904,7 @@ class    go to state 5
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
 
@@ -973,7 +973,7 @@ class    go to state 5
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
 
@@ -1063,7 +1063,7 @@ class    go to state 5
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
 
@@ -1180,7 +1180,7 @@ class    go to state 5
 
 %%
         INPUT
-        grammar = Lrama::NewParser.new(y, nil).parse
+        grammar = Lrama::NewParser.new(y).parse
         states = Lrama::States.new(grammar, warning)
         states.compute
 
@@ -1426,7 +1426,7 @@ class    go to state 5
 
 %%
       INPUT
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -1598,7 +1598,7 @@ class    go to state 5
 
 %%
       INPUT
-      grammar = Lrama::NewParser.new(y, nil).parse
+      grammar = Lrama::NewParser.new(y).parse
       states = Lrama::States.new(grammar, warning)
       states.compute
 
@@ -1816,7 +1816,7 @@ class : keyword_class tSTRING keyword_end %prec tPLUS
           end
 
           it "has errors for r/r conflicts" do
-            grammar = Lrama::NewParser.new(header + y, nil).parse
+            grammar = Lrama::NewParser.new(header + y).parse
             states = Lrama::States.new(grammar, warning)
             states.compute
 
@@ -1840,7 +1840,7 @@ class : keyword_class tSTRING keyword_end %prec tPLUS
           end
 
           it "has errors for s/r conflicts and r/r conflicts" do
-            grammar = Lrama::NewParser.new(header + y, nil).parse
+            grammar = Lrama::NewParser.new(header + y).parse
             states = Lrama::States.new(grammar, warning)
             states.compute
 
@@ -1864,7 +1864,7 @@ class : keyword_class tSTRING keyword_end %prec tPLUS
         end
 
         it "has warns for s/r conflicts and r/r conflicts" do
-          grammar = Lrama::NewParser.new(header + y, nil).parse
+          grammar = Lrama::NewParser.new(header + y).parse
           states = Lrama::States.new(grammar, warning)
           states.compute
 
diff --git a/template/bison/yacc.c b/template/bison/yacc.c
index 8f57984e..06a13ac1 100644
--- a/template/bison/yacc.c
+++ b/template/bison/yacc.c
@@ -101,8 +101,12 @@
 # endif
 
 <%# b4_header_include_if -%>
+<%- if output.include_header -%>
+#include "<%= output.include_header %>"
+<%- else -%>
 /* Use api.header.include to #include this header
    instead of duplicating it here.  */
+<%- end -%>
 <%# b4_shared_declarations -%>
   <%-# b4_cpp_guard_open([b4_spec_mapped_header_file]) -%>
     <%- if output.spec_mapped_header_file -%>