diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index 187a4aa..ae23464 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -913,7 +913,7 @@ class Executor
             }
         }
 
-        return $property instanceof \Closure ? $property($source, $args, $context) : $property;
+        return is_callable($property) ? $property($source, $args, $context) : $property;
     }
 
     /**
diff --git a/tests/Executor/ResolveTest.php b/tests/Executor/ResolveTest.php
index f3f6cf4..49e23b6 100644
--- a/tests/Executor/ResolveTest.php
+++ b/tests/Executor/ResolveTest.php
@@ -60,6 +60,23 @@ class ResolveTest extends \PHPUnit_Framework_TestCase
         );
     }
 
+    /**
+     * @it default function calls callables
+     */
+    public function testDefaultFunctionCallsCallables()
+    {
+        $schema = $this->buildSchema(['type' => Type::string()]);
+        $_secret = 'secretValue' . uniqid();
+
+        $source = [
+            'test' => new ResolveTestCallableFixture($_secret)
+        ];
+        $this->assertEquals(
+            ['data' => ['test' => $_secret]],
+            GraphQL::execute($schema, '{ test }', $source)
+        );
+    }
+
     /**
      * @it default function passes args and context
      */
@@ -114,4 +131,19 @@ class ResolveTest extends \PHPUnit_Framework_TestCase
             GraphQL::execute($schema, '{ test(aInt: -123, aStr: "String!") }', 'Source!')
         );
     }
-}
\ No newline at end of file
+}
+
+class ResolveTestCallableFixture
+{
+    private $value;
+
+    public function __construct($value)
+    {
+        $this->value = $value;
+    }
+
+    public function __invoke($root, $args, $context)
+    {
+        return $this->value;
+    }
+}