diff --git a/doc-src/HAML_CHANGELOG.md b/doc-src/HAML_CHANGELOG.md
index 413a4219..cc3cccce 100644
--- a/doc-src/HAML_CHANGELOG.md
+++ b/doc-src/HAML_CHANGELOG.md
@@ -140,6 +140,9 @@ that surrounds the filtered text with `<style>` and CDATA tags.
 
 * Don't crash when parsing an XHTML Strict doctype in `html2haml`.
 
+* Support the  HTML5 doctype in an XHTML document
+  by using `!!! 5` as the doctype declaration.
+
 ## [2.2.13](http://github.com/nex3/haml/commit/2.2.13)
 
 * Allow users to specify {file:HAML_REFERENCE.md#encoding_option `:encoding => "ascii-8bit"`}
diff --git a/doc-src/HAML_REFERENCE.md b/doc-src/HAML_REFERENCE.md
index 3ee936c2..4d7e5017 100644
--- a/doc-src/HAML_REFERENCE.md
+++ b/doc-src/HAML_REFERENCE.md
@@ -664,40 +664,55 @@ is compiled to:
       </body>
     </html>
 
-You can also specify the version and type of XHTML after the `!!!`.
-XHTML 1.0 Strict, Transitional, and Frameset and XHTML 1.1 are supported.
-The default version is 1.0 and the default type is Transitional.
-For example:
+You can also specify the specific doctype after the `!!!`
+When the [`:format`](#format) is set to `:xhtml` (the default),
+the following doctypes are supported:
 
-    !!! 1.1
+`!!!`
+: XHTML 1.0 Transitional<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">`
 
-is compiled to:
+`!!! Strict`
+: XHTML 1.0 Strict<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">`
 
-    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
+`!!! Frameset`
+: XHTML 1.0 Frameset<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">`
 
-and
+`!!! 5`
+: XHTML 5<br/>
+ `<!DOCTYPE html>`<br/>
 
-    !!! Strict
+`!!! 1.1`
+: XHTML 1.1<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">`
 
-is compiled to:
+`!!! Basic`
+: XHTML Basic 1.1<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd"> `
 
-    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+`!!! Mobile`
+: XHTML Mobile 1.2<br/>
+ `<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN" "http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">`
 
-while 
+When the [`:format`](#format) option is set to `:html4`,
+the following doctypes are supported:
 
-    !!! Basic
+`!!!`
+: HTML 4.01 Transitional<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">`
 
-is compiled to:
+`!!! Strict`
+: HTML 4.01 Strict<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">`
 
-    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN" "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd"> 
+`!!! Frameset`
+: HTML 4.01 Frameset<br/>
+ `<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">`
 
-and
-  
-    !!! Mobile
-
-is compiled to: 
-
-    <!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.2//EN" "http://www.openmobilealliance.org/tech/DTD/xhtml-mobile12.dtd">
+When the [`:format`](#format) option is set to `:html5`,
+`!!!` is always `<!DOCTYPE html>`.
 
 If you're not using the UTF-8 character set for your document,
 you can specify which encoding should appear
diff --git a/lib/haml/precompiler.rb b/lib/haml/precompiler.rb
index 86c05821..62eb9eac 100644
--- a/lib/haml/precompiler.rb
+++ b/lib/haml/precompiler.rb
@@ -82,7 +82,7 @@ module Haml
     MID_BLOCK_KEYWORD_REGEX = /^-\s*(#{%w[else elsif rescue ensure when end].join('|')})\b/
 
     # The Regex that matches a Doctype command.
-    DOCTYPE_REGEX = /(\d\.\d)?[\s]*([a-z]*)/i
+    DOCTYPE_REGEX = /(\d(?:\.\d)?)?[\s]*([a-z]*)/i
 
     # The Regex that matches a literal string or symbol value
     LITERAL_VALUE_REGEX = /:(\w*)|(["'])((?![\\#]|\2).|\\.)*\2/
@@ -857,6 +857,8 @@ END
         if xhtml?
           if version == "1.1"
             '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">'
+          elsif version == "5"
+            '<!DOCTYPE html>'
           else
             case type
             when "strict";   '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">'
diff --git a/test/haml/engine_test.rb b/test/haml/engine_test.rb
index 15ce796b..70376878 100644
--- a/test/haml/engine_test.rb
+++ b/test/haml/engine_test.rb
@@ -734,6 +734,7 @@ HAML
   def test_doctypes
     assert_equal('<!DOCTYPE html>',
       render('!!!', :format => :html5).strip)
+    assert_equal('<!DOCTYPE html>', render('!!! 5').strip)
     assert_equal('<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">',
       render('!!! strict').strip)
     assert_equal('<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">',
