diff --git a/lib/common.js b/lib/common.js
index 9d9cfe65..2db7dc81 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -26,7 +26,7 @@ var OPENTAG = "<" + TAGNAME + ATTRIBUTE + "*" + "\\s*/?>";
 var CLOSETAG = "</" + TAGNAME + "\\s*[>]";
 var HTMLCOMMENT = "<!-->|<!--->|<!--(?:[^-]|-[^-]|--[^>])*-->"
 var PROCESSINGINSTRUCTION = "[<][?][\\s\\S]*?[?][>]";
-var DECLARATION = "<![A-Z]+" + "[^>]*>";
+var DECLARATION = "<![A-Za-z]+" + "[^>]*>";
 var CDATA = "<!\\[CDATA\\[[\\s\\S]*?\\]\\]>";
 var HTMLTAG =
     "(?:" +
diff --git a/test/regression.txt b/test/regression.txt
index aea81378..bf34ab6c 100644
--- a/test/regression.txt
+++ b/test/regression.txt
@@ -491,4 +491,14 @@ x <- 1
 ""third [test]
 .
 <p>&quot;&quot;third <a href="example">test</a></p>
-````````````````````````````````
\ No newline at end of file
+````````````````````````````````
+
+#283
+```````````````````````````````` example
+x<!x>
+
+x<!>
+.
+<p>x<!x></p>
+<p>x&lt;!&gt;</p>
+````````````````````````````````