diff --git a/ext/ripper/tools/preproc.rb b/ext/ripper/tools/preproc.rb
index 981237a585..a36c98689b 100644
--- a/ext/ripper/tools/preproc.rb
+++ b/ext/ripper/tools/preproc.rb
@@ -53,7 +53,6 @@ end
 
 def prelude(f, out)
   @exprs = {}
-  lex_state_def = false
   while line = f.gets
     case line
     when /\A%%/
@@ -62,24 +61,18 @@ def prelude(f, out)
     when /\A%token/, /\A%type/, /\A} <node(?>_\w+)?>/
       # types in %union which have corresponding set_yylval_* macro.
       out << line
-    when /^enum lex_state_(?:bits|e) \{/
-      lex_state_def = true
-      out << line
-    when /^\}/
-      lex_state_def = false
-      out << line
     else
-      out << line
-    end
-    if lex_state_def
-      case line
-      when /^\s*(EXPR_\w+),\s+\/\*(.+)\*\//
-        @exprs[$1.chomp("_bit")] = $2.strip
-      when /^\s*(EXPR_\w+)\s+=\s+(.+)$/
-        name = $1
-        val = $2.chomp(",")
-        @exprs[name] = "equals to " + (val.start_with?("(") ? "<tt>#{val}</tt>" : "+#{val}+")
+      if (/^enum lex_state_(?:bits|e) \{/ =~ line)..(/^\}/ =~ line)
+        case line
+        when /^\s*(EXPR_\w+),\s+\/\*(.+)\*\//
+          @exprs[$1.chomp("_bit")] = $2.strip
+        when /^\s*(EXPR_\w+)\s+=\s+(.+)$/
+          name = $1
+          val = $2.chomp(",")
+          @exprs[name] = "equals to " + (val.start_with?("(") ? "<tt>#{val}</tt>" : "+#{val}+")
+        end
       end
+      out << line
     end
   end
 end
diff --git a/template/encdb.h.tmpl b/template/encdb.h.tmpl
index 8e658f7985..81d27afa1b 100644
--- a/template/encdb.h.tmpl
+++ b/template/encdb.h.tmpl
@@ -40,28 +40,20 @@ encdirs.each do |encdir|
     files[fn] = true
     open(File.join(encdir,fn)) do |f|
       name = nil
-      skip_ifndef_ruby = false
-      encoding_def = false
       f.each_line do |line|
-        case line
-        when /^#ifndef RUBY/
-          skip_ifndef_ruby = true
-        when /^#endif/
-          skip_ifndef_ruby = false
-        end
-        next if skip_ifndef_ruby
-        encoding_def = true if /^OnigEncodingDefine/ =~ line
-        if encoding_def && /"(.*?)"/ =~ line
-          encoding_def = false
-          if name
-            lines << %[ENC_SET_BASE("#$1", "#{name}");]
-          else
-            name = $1
+        if (/^#ifndef RUBY/ =~ line)..(/^#endif/ =~ line)
+        elsif (/^OnigEncodingDefine/ =~ line)..(/"(.*?)"/ =~ line)
+          if $1
+            if name
+              lines << %[ENC_SET_BASE("#$1", "#{name}");]
+            else
+              name = $1
+            end
+            check_duplication(defs, $1, fn, f.lineno)
+            next if BUILTIN_ENCODINGS[name]
+            encodings << $1
+            count += 1
           end
-          check_duplication(defs, $1, fn, f.lineno)
-          next if BUILTIN_ENCODINGS[name]
-          encodings << $1
-          count += 1
         else
           case line
           when /^\s*rb_enc_register\(\s*"([^"]+)"/
diff --git a/template/transdb.h.tmpl b/template/transdb.h.tmpl
index 990a8639d0..6ba159ea47 100644
--- a/template/transdb.h.tmpl
+++ b/template/transdb.h.tmpl
@@ -36,18 +36,17 @@ transdirs.each do |transdir|
     files[fn] = true
     path = File.join(transdir,fn)
     open(path) do |f|
-      transcoder_def = false
       f.each_line do |line|
-        transcoder_def = true if /^static const rb_transcoder/ =~ line
-        if transcoder_def && /"(.*?)"\s*,\s*"(.*?)"/ =~ line
-          transcoder_def = false
-          from_to = "%s to %s" % [$1, $2]
-          if converters[from_to]
-            raise ArgumentError, '%s:%d: transcode "%s" is already registered at %s:%d' %
-            [path, f.lineno, from_to, *converters[from_to].values_at(3, 4)]
-          else
-            converters[from_to] = [$1, $2, fn[0..-3], path, f.lineno]
-            converter_list << from_to
+        if (/^static const rb_transcoder/ =~ line)..(/"(.*?)"\s*,\s*"(.*?)"/ =~ line)
+          if $1 && $2
+            from_to = "%s to %s" % [$1, $2]
+            if converters[from_to]
+              raise ArgumentError, '%s:%d: transcode "%s" is already registered at %s:%d' %
+              [path, f.lineno, from_to, *converters[from_to].values_at(3, 4)]
+            else
+              converters[from_to] = [$1, $2, fn[0..-3], path, f.lineno]
+              converter_list << from_to
+            end
           end
         end
       end