diff --git a/CHANGELOG b/CHANGELOG
index 1a0807c9f..4d2c72fc3 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,6 @@
 * 1.28.0 (2016-XX-XX)
 
- * added "is defined" support for block()
+ * added "is defined" support for block() and constant()
  * optimized the way attributes are fetched
 
 * 1.27.0 (2016-10-25)
diff --git a/doc/functions/constant.rst b/doc/functions/constant.rst
index bea0e9fc0..9c1ed23fd 100644
--- a/doc/functions/constant.rst
+++ b/doc/functions/constant.rst
@@ -16,3 +16,11 @@ As of 1.12.1 you can read constants from object instances as well:
 .. code-block:: jinja
 
     {{ constant('RSS', date) }}
+
+Use the ``defined`` test to check if a constant is defined:
+
+.. code-block:: jinja
+
+    {% if constant('SOME_CONST') is defined %}
+        ...
+    {% endif %}
diff --git a/lib/Twig/Extension/Core.php b/lib/Twig/Extension/Core.php
index 901a3058f..9ddb627cc 100644
--- a/lib/Twig/Extension/Core.php
+++ b/lib/Twig/Extension/Core.php
@@ -1452,6 +1452,23 @@ function twig_constant($constant, $object = null)
     return constant($constant);
 }
 
+/**
+ * Checks if a constant exists.
+ *
+ * @param string      $constant The name of the constant
+ * @param null|object $object   The object to get the constant from
+ *
+ * @return bool
+ */
+function twig_constant_is_defined($constant, $object = null)
+{
+    if (null !== $object) {
+        $constant = get_class($object).'::'.$constant;
+    }
+
+    return defined($constant);
+}
+
 /**
  * Batches item.
  *
diff --git a/lib/Twig/Node/Expression/Function.php b/lib/Twig/Node/Expression/Function.php
index 7326ede26..207f6552b 100644
--- a/lib/Twig/Node/Expression/Function.php
+++ b/lib/Twig/Node/Expression/Function.php
@@ -12,7 +12,7 @@ class Twig_Node_Expression_Function extends Twig_Node_Expression_Call
 {
     public function __construct($name, Twig_NodeInterface $arguments, $lineno)
     {
-        parent::__construct(array('arguments' => $arguments), array('name' => $name), $lineno);
+        parent::__construct(array('arguments' => $arguments), array('name' => $name, 'is_defined_test' => false), $lineno);
     }
 
     public function compile(Twig_Compiler $compiler)
@@ -27,7 +27,12 @@ class Twig_Node_Expression_Function extends Twig_Node_Expression_Call
         $this->setAttribute('needs_context', $function->needsContext());
         $this->setAttribute('arguments', $function->getArguments());
         if ($function instanceof Twig_FunctionCallableInterface || $function instanceof Twig_SimpleFunction) {
-            $this->setAttribute('callable', $function->getCallable());
+            $callable = $function->getCallable();
+            if ('constant' === $name && $this->getAttribute('is_defined_test')) {
+                $callable = 'twig_constant_is_defined';
+            }
+
+            $this->setAttribute('callable', $callable);
         }
         if ($function instanceof Twig_SimpleFunction) {
             $this->setAttribute('is_variadic', $function->isVariadic());
diff --git a/lib/Twig/Node/Expression/Test/Defined.php b/lib/Twig/Node/Expression/Test/Defined.php
index a8fd74db9..9d2d7ca72 100644
--- a/lib/Twig/Node/Expression/Test/Defined.php
+++ b/lib/Twig/Node/Expression/Test/Defined.php
@@ -32,6 +32,8 @@ class Twig_Node_Expression_Test_Defined extends Twig_Node_Expression_Test
             $this->changeIgnoreStrictCheck($node);
         } elseif ($node instanceof Twig_Node_Expression_BlockReference) {
             $node->setAttribute('is_defined_test', true);
+        } elseif ($node instanceof Twig_Node_Expression_Function && 'constant' === $node->getAttribute('name')) {
+            $node->setAttribute('is_defined_test', true);
         } elseif ($node instanceof Twig_Node_Expression_Constant || $node instanceof Twig_Node_Expression_Array) {
             $node = new Twig_Node_Expression_Constant(true, $node->getTemplateLine());
         } else {
diff --git a/test/Twig/Tests/Fixtures/tests/defined_for_constants.test b/test/Twig/Tests/Fixtures/tests/defined_for_constants.test
new file mode 100644
index 000000000..2fa9929d3
--- /dev/null
+++ b/test/Twig/Tests/Fixtures/tests/defined_for_constants.test
@@ -0,0 +1,14 @@
+--TEST--
+"defined" support for constants
+--TEMPLATE--
+{{ constant('DATE_W3C') is defined ? 'ok' : 'ko' }}
+{{ constant('ARRAY_AS_PROPS', object) is defined ? 'ok' : 'ko' }}
+{{ constant('FOOBAR') is not defined ? 'ok' : 'ko' }}
+{{ constant('FOOBAR', object) is not defined ? 'ok' : 'ko' }}
+--DATA--
+return array('expect' => DATE_W3C, 'object' => new ArrayObject(array('hi')));
+--EXPECT--
+ok
+ok
+ok
+ok