diff --git a/ext/dom/dom_iterators.c b/ext/dom/dom_iterators.c
index 866cb5a07e99f..d22cb0699fe59 100644
--- a/ext/dom/dom_iterators.c
+++ b/ext/dom/dom_iterators.c
@@ -184,13 +184,15 @@ static void php_dom_iterator_move_forward(zend_object_iterator *iter) /* {{{ */
 	bool do_curobj_undef = 1;
 
 	php_dom_iterator *iterator = (php_dom_iterator *)iter;
+	if (Z_ISUNDEF(iterator->curobj)) {
+		return;
+	}
 
+	intern = Z_DOMOBJ_P(&iterator->curobj);
 	object = &iterator->intern.data;
 	nnmap = Z_DOMOBJ_P(object);
 	objmap = (dom_nnodemap_object *)nnmap->ptr;
 
-	intern = Z_DOMOBJ_P(&iterator->curobj);
-
 	if (intern != NULL && intern->ptr != NULL) {
 		if (objmap->nodetype != XML_ENTITY_NODE &&
 			objmap->nodetype != XML_NOTATION_NODE) {
diff --git a/ext/dom/tests/gh15551.phpt b/ext/dom/tests/gh15551.phpt
new file mode 100644
index 0000000000000..3b4b7d4e85793
--- /dev/null
+++ b/ext/dom/tests/gh15551.phpt
@@ -0,0 +1,14 @@
+--TEST--
+GH-15551 (Segmentation fault (access null pointer) in ext/dom/xml_common.h)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+$fragment = new DOMDocumentFragment();
+$nodes = $fragment->childNodes;
+$iter = $nodes->getIterator();
+$iter->next();
+var_dump($iter->valid());
+?>
+--EXPECT--
+bool(false)