diff --git a/lib/oga/html/parser.rb b/lib/oga/html/parser.rb
index bc12cc1..2395269 100644
--- a/lib/oga/html/parser.rb
+++ b/lib/oga/html/parser.rb
@@ -6,13 +6,14 @@ module Oga
     #
     class Parser < XML::Parser
       ##
+      # @param [String] data
       # @param [Hash] options
       # @see Oga::XML::Parser#initialize
       #
-      def initialize(options = {})
+      def initialize(data, options = {})
         options = options.merge(:html => true)
 
-        super(options)
+        super(data, options)
       end
     end # Parser
   end # HTML
diff --git a/lib/oga/xml/lexer.rl b/lib/oga/xml/lexer.rl
index 75667de..6afa0c4 100644
--- a/lib/oga/xml/lexer.rl
+++ b/lib/oga/xml/lexer.rl
@@ -53,17 +53,21 @@ module Oga
       end
 
       ##
+      # @param [String] data The data to lex.
+      #
       # @param [Hash] options
       #
       # @option options [Symbol] :html When set to `true` the lexer will treat
       # the input as HTML instead of SGML/XML. This makes it possible to lex
       # HTML void elements such as `<link href="">`.
       #
-      def initialize(options = {})
+      def initialize(data, options = {})
         options.each do |key, value|
           instance_variable_set("@#{key}", value) if respond_to?(key)
         end
 
+        @data = data.unpack('U*')
+
         reset
       end
 
@@ -74,7 +78,6 @@ module Oga
       #
       def reset
         @line     = 1
-        @data     = nil
         @ts       = nil
         @te       = nil
         @tokens   = []
@@ -83,6 +86,9 @@ module Oga
         @cs       = self.class.lexer_start
         @act      = 0
         @elements = []
+        @eof      = @data.length
+        @p        = 0
+        @pe       = @eof
 
         @buffer_start_position = nil
       end
@@ -102,8 +108,12 @@ module Oga
       # @return [Array]
       # @see #advance
       #
-      def lex(data)
-        tokens = advance(data)
+      def lex
+        tokens = []
+
+        while token = advance
+          tokens << token
+        end
 
         reset
 
@@ -118,16 +128,10 @@ module Oga
       # @param [String] data The String to consume.
       # @return [Array]
       #
-      def advance(data)
-        @data = data.unpack('U*')
-        eof   = data.length
-
-        p  = 0
-        pe = eof
-
+      def advance
         %% write exec; # % fix highlight
 
-        return @tokens
+        return @tokens.shift
       end
 
       ##
@@ -244,7 +248,10 @@ module Oga
       %%{
         # Use instance variables for `ts` and friends.
         access @;
-        getkey (@data[p] || 0);
+        getkey (@data[@p] || 0);
+        variable p @p;
+        variable pe @pe;
+        variable eof @eof;
 
         newline    = '\n' | '\r\n';
         whitespace = [ \t];
@@ -529,7 +536,7 @@ module Oga
             start_buffer(@ts) unless buffering?
 
             # EOF, emit the text buffer.
-            if @te == eof
+            if @te == @eof
               emit_buffer(@te)
             end
           };
diff --git a/lib/oga/xml/parser.y b/lib/oga/xml/parser.y
index ed555b5..27b366d 100644
--- a/lib/oga/xml/parser.y
+++ b/lib/oga/xml/parser.y
@@ -135,13 +135,14 @@ end
 
 ---- inner
   ##
+  # @param [String] data The input to parse.
+  #
   # @param [Hash] options
+  # @see Oga::XML::Lexer#initialize
   #
-  # @option options [TrueClass|FalseClass] :html Enables HTML parsing mode.
-  # @see Oga::Lexer#initialize
-  #
-  def initialize(options = {})
-    @lexer = Lexer.new(options)
+  def initialize(data, options = {})
+    @data  = data
+    @lexer = Lexer.new(data, options)
   end
 
   ##
@@ -172,7 +173,7 @@ end
   # @return [Array]
   #
   def next_token
-    type, value, line = @tokens.shift
+    type, value, line = @lexer.advance
 
     @line = line if line
 
@@ -188,11 +189,12 @@ end
   def on_error(type, value, stack)
     name  = token_to_str(type)
     index = @line - 1
-    lines = ''
+    lines = @data.lines.to_a
+    code  = ''
 
     # Show up to 5 lines before and after the offending line (if they exist).
     (-5..5).each do |offset|
-      line   = @lines[index + offset]
+      line   = lines[index + offset]
       number = @line + offset
 
       if line and number > 0
@@ -202,31 +204,28 @@ end
           prefix = '   '
         end
 
-        lines << "#{prefix}#{number}: #{line.strip}\n"
+        code << "#{prefix}#{number}: #{line.strip}\n"
       end
     end
 
     raise Racc::ParseError, <<-EOF.strip
 Unexpected #{name} with value #{value.inspect} on line #{@line}:
 
-#{lines}
+#{code}
     EOF
   end
 
   ##
-  # Parses the supplied string and returns the AST.
+  # Parses the input and returns the corresponding AST.
   #
   # @example
-  #  parser = Oga::Parser.new
-  #  ast    = parser.parse('<foo>bar</foo>')
+  #  parser = Oga::Parser.new('<foo>bar</foo>')
+  #  ast    = parser.parse
   #
-  # @param [String] string
   # @return [Oga::AST::Node]
   #
-  def parse(string)
-    @lines  = string.lines
-    @tokens = @lexer.lex(string)
-    ast     = do_parse
+  def parse
+    ast = do_parse
 
     reset
 
diff --git a/spec/support/parsing.rb b/spec/support/parsing.rb
index 9e347bd..5486708 100644
--- a/spec/support/parsing.rb
+++ b/spec/support/parsing.rb
@@ -19,7 +19,7 @@ module Oga
     # @return [Array]
     #
     def lex(input, options = {})
-      return Oga::XML::Lexer.new(options).lex(input)
+      return Oga::XML::Lexer.new(input, options).lex
     end
 
     ##
@@ -30,7 +30,7 @@ module Oga
     # @return [Oga::AST::Node]
     #
     def parse(input, options = {})
-      return Oga::XML::Parser.new(options).parse(input)
+      return Oga::XML::Parser.new(input, options).parse
     end
 
     ##
@@ -39,7 +39,7 @@ module Oga
     # @see #parse
     #
     def parse_html(input, options = {})
-      return Oga::HTML::Parser.new(options).parse(input)
+      return Oga::HTML::Parser.new(input, options).parse
     end
 
     ##