diff --git a/src/main/php/lang/ast/Tokens.class.php b/src/main/php/lang/ast/Tokens.class.php
index bc4303a..c8b278f 100755
--- a/src/main/php/lang/ast/Tokens.class.php
+++ b/src/main/php/lang/ast/Tokens.class.php
@@ -12,7 +12,7 @@
 class Tokens {
   const DELIMITERS = " \r\n\t'\$\"`=,;.:?!(){}[]#+-*/|&^@%~<>";
   const OPERATORS = [
-    '<' => ['<=>', '<<=', '<=', '<<', '<>', '<?'],
+    '<' => ['<=>', '<<=', '<<<', '<=', '<<', '<>', '<?'],
     '>' => ['>>=', '>=', '>>'],
     '=' => ['===', '=>', '=='],
     '!' => ['!==', '!='],
@@ -22,7 +22,7 @@ class Tokens {
     '+' => ['+=', '++'],
     '-' => ['-=', '--', '->'],
     '*' => ['**=', '*=', '**'],
-    '/' => ['/='],
+    '/' => ['/=', '//', '/*'],
     '~' => ['~='],
     '%' => ['%='],
     '?' => ['?->', '??=', '?:', '??'],
@@ -106,10 +106,10 @@ public function iterator($language) {
         $end= '\\'.$token;
         do {
           $chunk= $next($end);
-          if (null === $chunk) {
-            throw new FormatException('Unclosed string literal starting at line '.$line);
-          } else if ('\\' === $chunk) {
+          if ('\\' === $chunk) {
             $string.= $chunk.$next($end);
+          } else if (null === $chunk) {
+            throw new FormatException('Unclosed string literal starting at line '.$line);
           } else {
             $string.= $chunk;
           }
@@ -162,34 +162,17 @@ public function iterator($language) {
             goto number;
           }
           $offset-= strlen($t);
-        } else if ('/' === $token) {
-          $t= $next(self::DELIMITERS);
-          if ('/' === $t) {
-            yield new Token(null, 'comment', '//'.$next("\r\n"), $line);
-            continue;
-          } else if ('*' === $t) {
-            $comment= '';
-            do {
-              $chunk= $next('/');
-              $comment.= $chunk;
-            } while (null !== $chunk && '*' !== $chunk[strlen($chunk) - 1]);
-            $comment.= $next('/');
-            yield new Token(null, '*' === $comment[0] ? 'apidoc' : 'comment', '/*'.$comment, $line);
-            $line+= substr_count($comment, "\n");
-            continue;
-          }
-          null === $t || $offset-= strlen($t);
         }
 
         // Handle combined operators. First, ensure we have enough bytes in our buffer
         // Our longest operator is 3 characters, hardcode this here.
-        if (self::OPERATORS[$token]) {
+        if ($combined= self::OPERATORS[$token]) {
           $offset--;
           while ($offset + 3 > $length && $this->in->available()) {
             $buffer.= $this->in->read(8192);
             $length= strlen($buffer);
           }
-          foreach (self::OPERATORS[$token] as $operator) {
+          foreach ($combined as $operator) {
             if ($offset + strlen($operator) > $length) continue;
             if (0 === substr_compare($buffer, $operator, $offset, strlen($operator))) {
               $token= $operator;
@@ -197,8 +180,41 @@ public function iterator($language) {
             }
           }
           $offset+= strlen($token);
-        }
 
+          // Distinguish single- and multiline comments as well as heredoc from operators
+          if ('//' === $token) {
+            yield new Token(null, 'comment', '//'.$next("\r\n"), $line);
+            continue;
+          } else if ('/*' === $token) {
+            $comment= '';
+            do {
+              $chunk= $next('/');
+              $comment.= $chunk;
+            } while (null !== $chunk && '*' !== $chunk[strlen($chunk) - 1]);
+            $comment.= $next('/');
+            yield new Token(null, '*' === $comment[0] ? 'apidoc' : 'comment', '/*'.$comment, $line);
+            $line+= substr_count($comment, "\n");
+            continue;
+          } else if ('<<<' === $token) {
+            $label= $next("\r\n");
+            $end= trim($label, '"\'');
+            $l= strlen($end);
+            $string= "<<<{$label}";
+
+            heredoc: $token= $next("\r\n");
+            if (0 === substr_compare($token, $end, $p= strspn($token, ' '), $l)) {
+              $p+= $l;
+              $offset-= strlen($token) - $p;
+              yield new Token($language->symbol('(literal)'), 'heredoc', $string.substr($token, 0, $p), $line);
+              $line+= substr_count($string, "\n");
+              continue;
+            } else if (null === $token) {
+              throw new FormatException('Unclosed heredoc literal starting at line '.$line);
+            }
+            $string.= $token;
+            goto heredoc;
+          }
+        }
         yield new Token($language->symbol($token), 'operator', $token, $line);
       } else {
         yield new Token($language->symbols[$token] ?? $language->symbol('(name)'), 'name', $token, $line);
diff --git a/src/test/php/lang/ast/unittest/TokensTest.class.php b/src/test/php/lang/ast/unittest/TokensTest.class.php
index 267b45b..ca403c7 100755
--- a/src/test/php/lang/ast/unittest/TokensTest.class.php
+++ b/src/test/php/lang/ast/unittest/TokensTest.class.php
@@ -43,6 +43,11 @@ public function unclosed_string_literals($input) {
     (new Tokens($input))->iterator($this->language)->current();
   }
 
+  #[Test, Expect(class: FormatException::class, message: '/Unclosed heredoc literal/'), Values(['<<<EOD', "<<<EOD\n", "<<<EOD\nLine 1"])]
+  public function unclosed_heredoc_literals($input) {
+    (new Tokens($input))->iterator($this->language)->current();
+  }
+
   #[Test, Values(['0', '1', '1_000_000_000'])]
   public function integer_literal($input) {
     $this->assertTokens([['integer' => str_replace('_', '', $input)]], new Tokens($input));
diff --git a/src/test/php/lang/ast/unittest/parse/LiteralsTest.class.php b/src/test/php/lang/ast/unittest/parse/LiteralsTest.class.php
index 1eb9273..cfc231d 100755
--- a/src/test/php/lang/ast/unittest/parse/LiteralsTest.class.php
+++ b/src/test/php/lang/ast/unittest/parse/LiteralsTest.class.php
@@ -86,4 +86,56 @@ public function dangling_comma_in_key_value_map($declaration) {
     $pair= [new Literal('"key"', self::LINE), new Literal('"value"', self::LINE)];
     $this->assertParsed([new ArrayLiteral([$pair], self::LINE)], $declaration);
   }
+
+  #[Test, Values(['EOD', '"EOD"', "'EOD'"])]
+  public function heredoc($label) {
+    $nowdoc= (
+      "<<<{$label}\n".
+      "Line 1\n".
+      "Line 2\n".
+      "\n".
+      "Line 4\n".
+      "EOD"
+    );
+    $this->assertParsed([new Literal($nowdoc, self::LINE)], $nowdoc.';');
+  }
+
+  #[Test]
+  public function heredoc_indentation() {
+    $nowdoc= (
+      "<<<EOD\n".
+      "  Line 1\n".
+      "  Line 2\n".
+      "\n".
+      "  Line 4\n".
+      "  EOD"
+    );
+    $this->assertParsed([new Literal($nowdoc, self::LINE)], $nowdoc.';');
+  }
+
+  #[Test]
+  public function line_number_after_multiline_string() {
+    $string= (
+      "'<html>\n".
+      "  ...\n".
+      "</html>'"
+    );
+    $this->assertParsed(
+      [new Literal($string, self::LINE), new Literal('null', self::LINE + 3)],
+      $string.";\nnull;"
+    );
+  }
+
+  #[Test]
+  public function line_number_after_heredoc() {
+    $nowdoc= (
+      "<<<EOD\n".
+      "  Line 1\n".
+      "  EOD"
+    );
+    $this->assertParsed(
+      [new Literal($nowdoc, self::LINE), new Literal('null', self::LINE + 3)],
+      $nowdoc.";\nnull;"
+    );
+  }
 }
\ No newline at end of file