diff --git a/ext/standard/tests/serialize/bug69210.phpt b/ext/standard/tests/serialize/bug69210.phpt
new file mode 100644
index 0000000000000..e9b6bf21da098
--- /dev/null
+++ b/ext/standard/tests/serialize/bug69210.phpt
@@ -0,0 +1,51 @@
+--TEST--
+serialize() integrity with non string on __sleep
+--FILE--
+<?php
+class testString
+{
+	public $a = true;
+
+	public function __sleep()
+	{
+		return array('a', '1');
+	}
+}
+
+class testInteger
+{
+	public $a = true;
+
+	public function __sleep()
+	{
+		return array('a', 1);
+	}
+}
+
+$cs = new testString();
+$ci = new testInteger();
+
+$ss =  @serialize($cs);
+echo $ss . "\n";
+
+$si = @serialize($ci);
+echo $si . "\n";
+
+var_dump(unserialize($ss));
+var_dump(unserialize($si));
+?>
+--EXPECT--
+O:10:"testString":2:{s:1:"a";b:1;s:1:"1";N;}
+O:11:"testInteger":2:{s:1:"a";b:1;s:1:"1";N;}
+object(testString)#3 (2) {
+  ["a"]=>
+  bool(true)
+  ["1"]=>
+  NULL
+}
+object(testInteger)#3 (2) {
+  ["a"]=>
+  bool(true)
+  ["1"]=>
+  NULL
+}
\ No newline at end of file
diff --git a/ext/standard/var.c b/ext/standard/var.c
index 1c5a000c2503b..ba8bf5db431f9 100644
--- a/ext/standard/var.c
+++ b/ext/standard/var.c
@@ -705,10 +705,7 @@ static void php_var_serialize_class(smart_str *buf, zval *struc, zval *retval_pt
 
 			if (Z_TYPE_P(name) != IS_STRING) {
 				php_error_docref(NULL, E_NOTICE, "__sleep should return an array only containing the names of instance-variables to serialize.");
-				/* we should still add element even if it's not OK,
-				 * since we already wrote the length of the array before */
-				smart_str_appendl(buf,"N;", 2);
-				continue;
+				convert_to_string(name);
 			}
 			propers = Z_OBJPROP_P(struc);
 			if ((d = zend_hash_find(propers, Z_STR_P(name))) != NULL) {