diff --git a/src/parser/html/PhutilHTMLParser.php b/src/parser/html/PhutilHTMLParser.php
--- a/src/parser/html/PhutilHTMLParser.php
+++ b/src/parser/html/PhutilHTMLParser.php
@@ -30,9 +30,13 @@
         continue;
       }
 
-      if (!$in_tag && ($c === '<')) {
+      // When we encounter a "<", we start a new tag whether we're already in
+      // a tag or not. We want to parse "<x>1 < 2</x>" as a single tag with
+      // the content "1 < 2".
+
+      if ($c === '<') {
         $segments[] = array(
-          'tag' => $in_tag,
+          'tag' => false,
           'pos' => $segment_pos,
           'end' => $ii,
         );
diff --git a/src/parser/html/__tests__/data/tag-angle.txt b/src/parser/html/__tests__/data/tag-angle.txt
new file mode 100644
--- /dev/null
+++ b/src/parser/html/__tests__/data/tag-angle.txt
@@ -0,0 +1,13 @@
+<math>1 < 2</math>
+~~~~~~~~~~
+[
+  {
+    "tag": "math",
+    "attributes": {},
+    "children": [
+      {
+        "content": "1 < 2"
+      }
+    ]
+  }
+]