diff --git a/Parsedown.php b/Parsedown.php
index ebc8097..8f36b8c 100755
--- a/Parsedown.php
+++ b/Parsedown.php
@@ -130,12 +130,12 @@ class Parsedown
 
                     if ( ! isset($block['closed']))
                     {
-                        if (strpos($line, $block['start']) !== false) # opening tag
+                        if (stripos($line, $block['start']) !== false) # opening tag
                         {
                             $block['depth']++;
                         }
 
-                        if (strpos($line, $block['end']) !== false) # closing tag
+                        if (stripos($line, $block['end']) !== false) # closing tag
                         {
                             if ($block['depth'] > 0)
                             {
@@ -359,8 +359,15 @@ class Parsedown
                         {
                             $name = $substring;
                         }
+                        $name = strtolower($name);
 
-                        if ( ! ctype_alpha($name))
+                        // hr,h1,h2,h3,h4,h5,h6 cases
+                        if ($name[0] == 'h' and strpos('r123456', $name[1]) !== false)
+                        {
+                            if ($name == 'hr')
+                                $is_self_closing = 1;
+                        }
+                        elseif ( ! ctype_alpha($name))
                         {
                             break;
                         }
@@ -392,7 +399,7 @@ class Parsedown
                             'depth' => 0,
                         );
 
-                        if (strpos($outdented_line, $block['end']))
+                        if (stripos($outdented_line, $block['end']))
                         {
                             $block['closed'] = true;
                         }
diff --git a/tests/data/html_simple.html b/tests/data/html_simple.html
new file mode 100644
index 0000000..61e50b6
--- /dev/null
+++ b/tests/data/html_simple.html
@@ -0,0 +1,28 @@
+<p>Headings:</p>
+<h2 id="overview">Overview</h2>
+<p>blah</p>
+<H2 id="block">Block Elements</H2>
+<p>blah</p>
+<h3 id="span">
+      Span Elements
+</h3>
+<p>blah</p>
+<p>Hr's:</p>
+<hr>
+<p>blah</p>
+<hr/>
+<p>blah</p>
+<hr />
+<p>blah</p>
+<hr>   
+<p>blah</p>
+<hr/>  
+<p>blah</p>
+<hr /> 
+<p>blah</p>
+<hr class="foo" id="bar" />
+<p>blah</p>
+<hr class="foo" id="bar"/>
+<p>blah</p>
+<hr class="foo" id="bar" >
+<p>blah</p>
\ No newline at end of file
diff --git a/tests/data/html_simple.md b/tests/data/html_simple.md
new file mode 100644
index 0000000..7b930df
--- /dev/null
+++ b/tests/data/html_simple.md
@@ -0,0 +1,39 @@
+Headings:
+
+<h2 id="overview">Overview</h2>
+blah
+<H2 id="block">Block Elements</H2>
+blah
+<h3 id="span">
+      Span Elements
+</h3>
+blah
+
+Hr's:
+
+<hr>
+blah
+
+<hr/>
+blah
+
+<hr />
+blah
+
+<hr>   
+blah
+
+<hr/>  
+blah
+
+<hr /> 
+blah
+
+<hr class="foo" id="bar" />
+blah
+
+<hr class="foo" id="bar"/>
+blah
+
+<hr class="foo" id="bar" >
+blah