diff --git a/html-tokenizer.cabal b/html-tokenizer.cabal
--- a/html-tokenizer.cabal
+++ b/html-tokenizer.cabal
@@ -1,7 +1,7 @@
 name:
   html-tokenizer
 version:
-  0.5.2
+  0.6
 synopsis:
   An "attoparsec"-based HTML tokenizer
 description:
diff --git a/library/HTMLTokenizer/Parsing.hs b/library/HTMLTokenizer/Parsing.hs
--- a/library/HTMLTokenizer/Parsing.hs
+++ b/library/HTMLTokenizer/Parsing.hs
@@ -139,13 +139,13 @@
 name :: Parser Name
 name =
   labeled "Name" $ do
-    c1 <- isolatedTextInsideTag
+    c1 <- D.toLower <$> isolatedTextInsideTag
     (mplus
       (do
         skipSpace
         char ':'
         skipSpace
-        c2 <- isolatedTextInsideTag
+        c2 <- D.toLower <$> isolatedTextInsideTag
         return (PrefixedName c1 c2))
       (return (UnprefixedName c1)))