diff --git a/NEWS b/NEWS
index 125c704b122..b1319961dc0 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,9 @@ PHP                                                                        NEWS
 - PHPDBG:
   . Fix crashes in function registration + test. (nielsdos, Girgias)
 
+- SimpleXML:
+  . Fixed bug GH-17409 (Assertion failure Zend/zend_hash.c:1730). (nielsdos)
+
 - SNMP:
   . Fixed bug GH-17330 (SNMP::setSecurity segfault on closed session).
     (David Carlier)
diff --git a/ext/simplexml/simplexml.c b/ext/simplexml/simplexml.c
index 00551267a45..18bfa31271e 100644
--- a/ext/simplexml/simplexml.c
+++ b/ext/simplexml/simplexml.c
@@ -2189,8 +2189,8 @@ static void sxe_object_free_storage(zend_object *object)
 	sxe_object_free_iterxpath(sxe);
 
 	if (sxe->properties) {
-		zend_hash_destroy(sxe->properties);
-		FREE_HASHTABLE(sxe->properties);
+		ZEND_ASSERT(!(GC_FLAGS(sxe->properties) & IS_ARRAY_IMMUTABLE));
+		zend_hash_release(sxe->properties);
 	}
 }
 /* }}} */
diff --git a/ext/simplexml/tests/gh17409.phpt b/ext/simplexml/tests/gh17409.phpt
new file mode 100644
index 00000000000..f91ef38ba70
--- /dev/null
+++ b/ext/simplexml/tests/gh17409.phpt
@@ -0,0 +1,22 @@
+--TEST--
+GH-17409 (Assertion failure Zend/zend_hash.c)
+--EXTENSIONS--
+simplexml
+--CREDITS--
+YuanchengJiang
+--FILE--
+<?php
+$root = simplexml_load_string('<?xml version="1.0"?>
+<root xmlns:reserved="reserved-ns">
+<child reserved:attribute="Sample" />
+</root>
+');
+// Need to use $GLOBALS such that simplexml object is destroyed
+var_dump(array_merge_recursive($GLOBALS, $GLOBALS)["root"]);
+?>
+--EXPECT--
+array(1) {
+  ["child"]=>
+  array(0) {
+  }
+}