diff --git a/after/syntax/css/css3-namespace.vim b/after/syntax/css/css3-namespace.vim
new file mode 100644
index 0000000..dd72adc
--- /dev/null
+++ b/after/syntax/css/css3-namespace.vim
@@ -0,0 +1 @@
+" N/A
diff --git a/after/syntax/html.vim b/after/syntax/html.vim
index 0f4524e..63ffc79 100644
--- a/after/syntax/html.vim
+++ b/after/syntax/html.vim
@@ -52,6 +52,7 @@ syn include @htmlCss syntax/css/css3-conditional.vim
 syn include @htmlCss syntax/css/css3-exclusions.vim
 syn include @htmlCss syntax/css/css3-images.vim
 syn include @htmlCss syntax/css/css3-multicol.vim
+syn include @htmlCss syntax/css/css3-namespace.vim
 syn include @htmlCss syntax/css/css3-page.vim
 syn include @htmlCss syntax/css/css3-speech.vim
 syn include @htmlCss syntax/css/css3-transitions.vim
diff --git a/test/test.css b/test/test.css
index bfd75e0..4d706c0 100644
--- a/test/test.css
+++ b/test/test.css
@@ -402,6 +402,8 @@
   column-width: auto;
 }
 
+@namespace "http://example.com/css3-namespace/";
+
 .overflow-3 {
   max-lines: auto;
 }
diff --git a/test/test.html b/test/test.html
index 5e8efed..346c470 100644
--- a/test/test.html
+++ b/test/test.html
@@ -445,6 +445,9 @@
 }
 </style>
 <style>
+@namespace "http://example.com/css3-namespace/";
+</style>
+<style>
 .overflow-3 {
   max-lines: auto;
 }