diff --git a/src/Briedis/ApiBuilder/StructureValidator.php b/src/Briedis/ApiBuilder/StructureValidator.php
index 24c84c6..7e05568 100644
--- a/src/Briedis/ApiBuilder/StructureValidator.php
+++ b/src/Briedis/ApiBuilder/StructureValidator.php
@@ -87,6 +87,10 @@ private function validateParam($name, $value)
         }
 
         if ($item instanceof StructureItem) {
+            if ($item->isOptional && is_null($value)) {
+                return;
+            }
+
             if ($item->isArray) {
                 $this->validateArrayOfStructures($item, $value);
                 return;
diff --git a/tests/MultiDepthValidatorTest.php b/tests/MultiDepthValidatorTest.php
index b9cc61b..4ec7c9f 100644
--- a/tests/MultiDepthValidatorTest.php
+++ b/tests/MultiDepthValidatorTest.php
@@ -245,4 +245,15 @@ public function testStructureOfArrayReceivesInvalidStructure()
 
         self::assertFalse(true, 'This should not execute');
     }
+
+    public function testOptionalStructuresCanBeNull()
+    {
+        $item = (new StructureBuilder('MyStructure'));
+
+        $whole = (new SB)->struct('item', $item)->optional();
+
+        $structureValidator = new StructureValidator($whole);
+
+        self::assertTrue($structureValidator->validate(['item' => null]));
+    }
 }
\ No newline at end of file