diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index 43382ca..3d91e78 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -70,8 +70,8 @@ rule
     ;
 
   class
-    : class_name             { s(:class, val[0]) }
-    | path_member class_name { s(:class, val[1], val[0]) }
+    : class_name             { s(:class, nil, val[0]) }
+    | path_member class_name { s(:class, val[0], val[1]) }
     ;
 
   class_name
@@ -79,8 +79,8 @@ rule
     ;
 
   id
-    : id_name             { s(:id, val[0]) }
-    | path_member id_name { s(:id, val[1], val[0]) }
+    : id_name             { s(:id, nil, val[0]) }
+    | path_member id_name { s(:id, val[0], val[1]) }
     ;
 
   id_name
diff --git a/spec/oga/css/parser/axes_spec.rb b/spec/oga/css/parser/axes_spec.rb
index e402d0a..64a0572 100644
--- a/spec/oga/css/parser/axes_spec.rb
+++ b/spec/oga/css/parser/axes_spec.rb
@@ -22,7 +22,7 @@ describe Oga::CSS::Parser do
       parse_css('x > foo#bar').should == s(
         :child,
         s(:test, nil, 'x'),
-        s(:id, 'bar', s(:test, nil, 'foo'))
+        s(:id, s(:test, nil, 'foo'), 'bar')
       )
     end
 
@@ -30,7 +30,7 @@ describe Oga::CSS::Parser do
       parse_css('x > foo.bar').should == s(
         :child,
         s(:test, nil, 'x'),
-        s(:class, 'bar', s(:test, nil, 'foo'))
+        s(:class, s(:test, nil, 'foo'), 'bar')
       )
     end
 
diff --git a/spec/oga/css/parser/classes_spec.rb b/spec/oga/css/parser/classes_spec.rb
index bb362b6..c879584 100644
--- a/spec/oga/css/parser/classes_spec.rb
+++ b/spec/oga/css/parser/classes_spec.rb
@@ -3,30 +3,30 @@ require 'spec_helper'
 describe Oga::CSS::Parser do
   context 'classes' do
     example 'parse a class selector' do
-      parse_css('.foo').should == s(:class, 'foo')
+      parse_css('.foo').should == s(:class, nil, 'foo')
     end
 
     example 'parse a selector for an element with a class' do
-      parse_css('foo.bar').should == s(:class, 'bar', s(:test, nil, 'foo'))
+      parse_css('foo.bar').should == s(:class, s(:test, nil, 'foo'), 'bar')
     end
 
     example 'parse a selector using multiple classes' do
-      parse_css('.foo.bar').should == s(:class, 'bar', s(:class, 'foo'))
+      parse_css('.foo.bar').should == s(:class, s(:class, nil, 'foo'), 'bar')
     end
 
     example 'parse a selector using a class and an ID' do
-      parse_css('#foo.bar').should == s(:class, 'bar', s(:id, 'foo'))
+      parse_css('#foo.bar').should == s(:class, s(:id, nil, 'foo'), 'bar')
     end
 
     example 'parse a selector using a class and a pseudo class' do
-      parse_css('.foo:root').should == s(:pseudo, 'root', s(:class, 'foo'))
+      parse_css('.foo:root').should == s(:pseudo, 'root', s(:class, nil, 'foo'))
     end
 
     example 'parse a selector using a pseudo class and a class' do
       parse_css('x:root.foo').should == s(
         :class,
-        'foo',
-        s(:pseudo, 'root', s(:test, nil, 'x'))
+        s(:pseudo, 'root', s(:test, nil, 'x')),
+        'foo'
       )
     end
   end
diff --git a/spec/oga/css/parser/ids_spec.rb b/spec/oga/css/parser/ids_spec.rb
index aeb0744..d93ea6e 100644
--- a/spec/oga/css/parser/ids_spec.rb
+++ b/spec/oga/css/parser/ids_spec.rb
@@ -3,26 +3,26 @@ require 'spec_helper'
 describe Oga::CSS::Parser do
   context 'IDs' do
     example 'parse an ID selector' do
-      parse_css('#foo').should == s(:id, 'foo')
+      parse_css('#foo').should == s(:id, nil, 'foo')
     end
 
     example 'parse a selector for an element with an ID' do
-      parse_css('foo#bar').should == s(:id, 'bar', s(:test, nil, 'foo'))
+      parse_css('foo#bar').should == s(:id, s(:test, nil, 'foo'), 'bar')
     end
 
     example 'parse a selector using an ID and a class' do
-      parse_css('.foo#bar').should == s(:id, 'bar', s(:class, 'foo'))
+      parse_css('.foo#bar').should == s(:id, s(:class, nil, 'foo'), 'bar')
     end
 
     example 'parse a selector using an ID and a pseudo class' do
-      parse_css('#foo:root').should == s(:pseudo, 'root', s(:id, 'foo'))
+      parse_css('#foo:root').should == s(:pseudo, 'root', s(:id, nil, 'foo'))
     end
 
     example 'parse a selector using a pseudo class and an ID' do
       parse_css('x:root#foo').should == s(
         :id,
-        'foo',
-        s(:pseudo, 'root', s(:test, nil, 'x'))
+        s(:pseudo, 'root', s(:test, nil, 'x')),
+        'foo'
       )
     end
   end