diff --git a/src/BSON/ObjectID.c b/src/BSON/ObjectID.c
index 774b01d4..1b2f7849 100644
--- a/src/BSON/ObjectID.c
+++ b/src/BSON/ObjectID.c
@@ -66,8 +66,7 @@ PHP_METHOD(ObjectID, __construct)
 	}
 	zend_restore_error_handling(&error_handling TSRMLS_CC);
 
-
-	if (ZEND_NUM_ARGS()) {
+	if (id) {
 		if (bson_oid_is_valid(id, id_len)) {
 			bson_oid_t oid;
 
diff --git a/tests/bson/bson-objectid-002.phpt b/tests/bson/bson-objectid-002.phpt
new file mode 100644
index 00000000..f0cd221b
--- /dev/null
+++ b/tests/bson/bson-objectid-002.phpt
@@ -0,0 +1,26 @@
+--TEST--
+BSON BSON\ObjectID #002 generates ObjectID for null or missing constructor argument
+--SKIPIF--
+<?php require __DIR__ . "/../utils/basic-skipif.inc"?>
+--FILE--
+<?php
+require_once __DIR__ . "/../utils/basic.inc";
+
+$classname = BSON_NAMESPACE . "\\ObjectID";
+
+var_dump(new $classname());
+var_dump(new $classname(null));
+
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECTF--
+object(MongoDB\BSON\ObjectID)#%d (%d) {
+  ["oid"]=>
+  string(24) "%x"
+}
+object(MongoDB\BSON\ObjectID)#%d (%d) {
+  ["oid"]=>
+  string(24) "%x"
+}
+===DONE===
diff --git a/tests/bson/bson-objectid-003.phpt b/tests/bson/bson-objectid-003.phpt
new file mode 100644
index 00000000..1a614d1d
--- /dev/null
+++ b/tests/bson/bson-objectid-003.phpt
@@ -0,0 +1,49 @@
+--TEST--
+BSON BSON\ObjectID #001 construction with string argument
+--SKIPIF--
+<?php require __DIR__ . "/../utils/basic-skipif.inc"?>
+--FILE--
+<?php
+require_once __DIR__ . "/../utils/basic.inc";
+
+$classname = BSON_NAMESPACE . "\\ObjectID";
+
+class StringObject
+{
+    private $value;
+
+    public function __construct($value)
+    {
+        $this->value = (string) $value;
+    }
+
+    public function __toString()
+    {
+        return $this->value;
+    }
+}
+
+$oid = new $classname('53e2a1c40640fd72175d4603');
+$str = new StringObject('53e2a1c40640fd72175d4603');
+
+var_dump($oid);
+var_dump(new $classname($oid));
+var_dump(new $classname($str));
+
+?>
+===DONE===
+<?php exit(0); ?>
+--EXPECTF--
+object(MongoDB\BSON\ObjectID)#%d (%d) {
+  ["oid"]=>
+  string(24) "53e2a1c40640fd72175d4603"
+}
+object(MongoDB\BSON\ObjectID)#%d (%d) {
+  ["oid"]=>
+  string(24) "53e2a1c40640fd72175d4603"
+}
+object(MongoDB\BSON\ObjectID)#%d (%d) {
+  ["oid"]=>
+  string(24) "53e2a1c40640fd72175d4603"
+}
+===DONE===