diff --git a/src/ExpressionParser.php b/src/ExpressionParser.php
index 66acddf61..70b6eb05c 100644
--- a/src/ExpressionParser.php
+++ b/src/ExpressionParser.php
@@ -485,7 +485,7 @@ class ExpressionParser
                     }
                 }
             } else {
-                throw new SyntaxError('Expected name or number.', $lineno, $stream->getSourceContext());
+                throw new SyntaxError(sprintf('Expected name or number, got value "%s" of type %s.', $token->getValue(), Token::typeToEnglish($token->getType())), $lineno, $stream->getSourceContext());
             }
 
             if ($node instanceof NameExpression && null !== $this->parser->getImportedSymbol('template', $node->getAttribute('name'))) {
diff --git a/src/Sandbox/SecurityPolicyInterface.php b/src/Sandbox/SecurityPolicyInterface.php
index 8eff61414..36471c54c 100644
--- a/src/Sandbox/SecurityPolicyInterface.php
+++ b/src/Sandbox/SecurityPolicyInterface.php
@@ -19,16 +19,26 @@ namespace Twig\Sandbox;
 interface SecurityPolicyInterface
 {
     /**
+     * @param string[] $tags
+     * @param string[] $filters
+     * @param string[] $functions
+     *
      * @throws SecurityError
      */
     public function checkSecurity($tags, $filters, $functions): void;
 
     /**
+     * @param object $obj
+     * @param string $method
+     *
      * @throws SecurityNotAllowedMethodError
      */
     public function checkMethodAllowed($obj, $method): void;
 
     /**
+     * @param object $obj
+     * @param string $property
+     *
      * @throws SecurityNotAllowedPropertyError
      */
     public function checkPropertyAllowed($obj, $property): void;
diff --git a/tests/Fixtures/expressions/dot_as_concatenation.test b/tests/Fixtures/expressions/dot_as_concatenation.test
new file mode 100644
index 000000000..7aa1403b6
--- /dev/null
+++ b/tests/Fixtures/expressions/dot_as_concatenation.test
@@ -0,0 +1,8 @@
+--TEST--
+Twig does not support using . for concatenation
+--TEMPLATE--
+{{ 'a'.'b' }}
+--DATA--
+return []
+--EXCEPTION--
+Twig\Error\SyntaxError: Expected name or number, got value "b" of type string in "index.twig" at line 2.