diff --git a/lib/oga/css/parser.y b/lib/oga/css/parser.y
index b7f5e8f..09e5b56 100644
--- a/lib/oga/css/parser.y
+++ b/lib/oga/css/parser.y
@@ -515,7 +515,11 @@ end
   # @return [AST::Node]
   #
   def on_pseudo_class_first_of_type
-    return s(:eq, s(:call, 'position'), s(:int, 1))
+    return s(
+      :eq,
+      s(:call, 'count', s(:axis, 'preceding-sibling', s(:call, 'name'))),
+      s(:int, 0)
+    )
   end
 
   ##
diff --git a/spec/oga/css/evaluator/pseudo_classes/first_of_type_spec.rb b/spec/oga/css/evaluator/pseudo_classes/first_of_type_spec.rb
index 8315926..e9bcdde 100644
--- a/spec/oga/css/evaluator/pseudo_classes/first_of_type_spec.rb
+++ b/spec/oga/css/evaluator/pseudo_classes/first_of_type_spec.rb
@@ -3,22 +3,25 @@ require 'spec_helper'
 describe 'CSS selector evaluation' do
   context ':first-of-type pseudo class' do
     before do
-      @document = parse('<root><a /><b /></root>')
+      @document = parse(<<-EOF)
+<dl>
+  <dt>foo</dt>
+  <dd>
+    <dl>
+      <dt>bar</dt>
+      <dd>baz</dd>
+    </dl>
+  </dd>
+</dl>
+      EOF
 
-      @a1 = @document.children[0].children[0]
-      @b1 = @document.children[0].children[1]
+      @dt1 = @document.at_xpath('dl/dt')
+      @dt2 = @document.at_xpath('dl/dd/dl/dt')
     end
 
-    example 'return a node set containing the first node' do
-      evaluate_css(@document, 'root :first-of-type').should == node_set(@a1)
-    end
-
-    example 'return a node set containing the first node with a node test' do
-      evaluate_css(@document, 'root a:first-of-type').should == node_set(@a1)
-    end
-
-    example 'return a node set containing the first <b> node' do
-      evaluate_css(@document, 'root b:first-of-type').should == node_set(@b1)
+    example 'return a node set containing all <dt> nodes' do
+      evaluate_css(@document, 'dl dt:first-of-type')
+        .should == node_set(@dt1, @dt2)
     end
   end
 end
diff --git a/spec/oga/css/parser/pseudo_classes/first_of_type_spec.rb b/spec/oga/css/parser/pseudo_classes/first_of_type_spec.rb
index 5e903a8..ae88987 100644
--- a/spec/oga/css/parser/pseudo_classes/first_of_type_spec.rb
+++ b/spec/oga/css/parser/pseudo_classes/first_of_type_spec.rb
@@ -4,7 +4,13 @@ describe Oga::CSS::Parser do
   context ':first-of-type pseudo class' do
     example 'parse the :first-of-type pseudo class' do
       parse_css(':first-of-type').should == parse_xpath(
-        'descendant::*[position() = 1]'
+        'descendant::*[count(preceding-sibling::name()) = 0]'
+      )
+    end
+
+    example 'parse the a:first-of-type pseudo class' do
+      parse_css('a:first-of-type').should == parse_xpath(
+        'descendant::a[count(preceding-sibling::name()) = 0]'
       )
     end
   end