diff --git a/src/Node/Expression/Unary/AbstractUnary.php b/src/Node/Expression/Unary/AbstractUnary.php
index d4746e73b..b00027d1a 100644
--- a/src/Node/Expression/Unary/AbstractUnary.php
+++ b/src/Node/Expression/Unary/AbstractUnary.php
@@ -16,7 +16,7 @@ use Twig\Compiler;
 use Twig\Node\Expression\AbstractExpression;
 use Twig\Node\Node;
 
-abstract class AbstractUnary extends AbstractExpression
+abstract class AbstractUnary extends AbstractExpression implements UnaryInterface
 {
     /**
      * @param AbstractExpression $node
diff --git a/src/Node/Expression/Unary/UnaryInterface.php b/src/Node/Expression/Unary/UnaryInterface.php
new file mode 100644
index 000000000..b094ef4f4
--- /dev/null
+++ b/src/Node/Expression/Unary/UnaryInterface.php
@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Twig\Node\Expression\Unary;
+
+use Twig\Node\Expression\AbstractExpression;
+
+/**
+ * @internal
+ */
+interface UnaryInterface
+{
+    public function __construct(AbstractExpression $node, int $lineno);
+}