diff --git a/src/infrastructure/markup/blockrule/PhutilRemarkupHeaderBlockRule.php b/src/infrastructure/markup/blockrule/PhutilRemarkupHeaderBlockRule.php
--- a/src/infrastructure/markup/blockrule/PhutilRemarkupHeaderBlockRule.php
+++ b/src/infrastructure/markup/blockrule/PhutilRemarkupHeaderBlockRule.php
@@ -73,12 +73,8 @@
   }
 
   private function generateAnchor($level, $text) {
-    $anchor = strtolower($text);
-    $anchor = preg_replace('/[^a-z0-9]/', '-', $anchor);
-    $anchor = preg_replace('/--+/', '-', $anchor);
-    $anchor = trim($anchor, '-');
-    $anchor = substr($anchor, 0, 24);
-    $anchor = trim($anchor, '-');
+    $anchor = self::getAnchorNameFromHeaderText($text);
+
     $base = $anchor;
 
     $key = self::KEY_HEADER_TOC;
@@ -159,4 +155,31 @@
     return phutil_implode_html("\n", $toc);
   }
 
+  public static function getAnchorNameFromHeaderText($text) {
+    $anchor = phutil_utf8_strtolower($text);
+
+    // Replace all latin characters which are not "a-z" or "0-9" with "-".
+    // Preserve other characters, since non-latin letters and emoji work
+    // fine in anchors.
+    $anchor = preg_replace('/[\x00-\x29\x3A-\x60\x7B-\x7F]+/', '-', $anchor);
+    $anchor = trim($anchor, '-');
+
+    // Truncate the fragment to something reasonable.
+    $anchor = id(new PhutilUTF8StringTruncator())
+      ->setMaximumGlyphs(32)
+      ->setTerminator('')
+      ->truncateString($anchor);
+
+    // If the fragment is terminated by a word which "The U.S. Government
+    // Printing Office Style Manual" normally discourages capitalizing in
+    // titles, discard it. This is an arbitrary heuristic intended to avoid
+    // awkward hanging words in anchors.
+    $anchor = preg_replace(
+      '/-(a|an|the|at|by|for|in|of|on|per|to|up|and|as|but|if|or|nor)\z/',
+      '',
+      $anchor);
+
+    return $anchor;
+  }
+
 }