diff --git a/NEWS b/NEWS
index 088501d1027..bb597215fb6 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,8 @@ PHP                                                                        NEWS
 - DOM:
   . Fixed bug GH-15551 (Segmentation fault (access null pointer) in
     ext/dom/xml_common.h). (nielsdos)
+  . Fixed bug GH-15654 (Signed integer overflow in ext/dom/nodelist.c).
+    (nielsdos)
 
 - MySQLnd:
   . Fixed bug GH-15432 (Heap corruption when querying a vector). (cmb,
diff --git a/ext/dom/dom_iterators.c b/ext/dom/dom_iterators.c
index dc4c83a7696..adc5835f9d8 100644
--- a/ext/dom/dom_iterators.c
+++ b/ext/dom/dom_iterators.c
@@ -179,7 +179,7 @@ static void php_dom_iterator_move_forward(zend_object_iterator *iter) /* {{{ */
 	dom_object *intern;
 	dom_object *nnmap;
 	dom_nnodemap_object *objmap;
-	int previndex;
+	zend_long previndex;
 	HashTable *nodeht;
 	zval *entry;
 	bool do_curobj_undef = 1;
@@ -269,7 +269,7 @@ zend_object_iterator *php_dom_get_iterator(zend_class_entry *ce, zval *object, i
 	dom_object *intern;
 	dom_nnodemap_object *objmap;
 	xmlNodePtr curnode=NULL;
-	int curindex = 0;
+	zend_long curindex = 0;
 	HashTable *nodeht;
 	zval *entry;
 	php_dom_iterator *iterator;
diff --git a/ext/dom/nodelist.c b/ext/dom/nodelist.c
index bb58161f16e..34767e048b5 100644
--- a/ext/dom/nodelist.c
+++ b/ext/dom/nodelist.c
@@ -91,7 +91,7 @@ int php_dom_get_nodelist_length(dom_object *obj)
 		reset_objmap_cache(objmap);
 	}
 
-	int count = 0;
+	zend_long count = 0;
 	if (objmap->nodetype == XML_ATTRIBUTE_NODE || objmap->nodetype == XML_ELEMENT_NODE) {
 		xmlNodePtr curnode = dom_nodelist_iter_start_first_child(nodep);
 		if (curnode) {
@@ -109,7 +109,7 @@ int php_dom_get_nodelist_length(dom_object *obj)
 			nodep = nodep->children;
 		}
 		dom_get_elements_by_tag_name_ns_raw(
-			basep, nodep, (char *) objmap->ns, (char *) objmap->local, &count, INT_MAX - 1 /* because of <= */);
+			basep, nodep, (char *) objmap->ns, (char *) objmap->local, &count, ZEND_LONG_MAX - 1 /* because of <= */);
 	}
 
 	objmap->cached_length = count;
@@ -174,7 +174,7 @@ void php_dom_nodelist_get_item_into_zval(dom_nnodemap_object *objmap, zend_long
 						 * TODO: in the future we could extend the logic of the node list such that backwards searches
 						 *       are also possible. */
 						bool restart = true;
-						int relative_index = index;
+						zend_long relative_index = index;
 						if (index >= objmap->cached_obj_index && objmap->cached_obj && !php_dom_is_cache_tag_stale_from_node(&objmap->cache_tag, nodep)) {
 							xmlNodePtr cached_obj_xml_node = dom_object_get_node(objmap->cached_obj);
 
@@ -192,7 +192,7 @@ void php_dom_nodelist_get_item_into_zval(dom_nnodemap_object *objmap, zend_long
 								nodep = cached_obj_xml_node;
 							}
 						}
-						int count = 0;
+						zend_long count = 0;
 						if (objmap->nodetype == XML_ATTRIBUTE_NODE || objmap->nodetype == XML_ELEMENT_NODE) {
 							if (restart) {
 								nodep = dom_nodelist_iter_start_first_child(nodep);
diff --git a/ext/dom/php_dom.c b/ext/dom/php_dom.c
index ff598f1ee54..5c7aacefba5 100644
--- a/ext/dom/php_dom.c
+++ b/ext/dom/php_dom.c
@@ -1334,7 +1334,7 @@ bool dom_has_feature(zend_string *feature, zend_string *version)
 }
 /* }}} end dom_has_feature */
 
-xmlNode *dom_get_elements_by_tag_name_ns_raw(xmlNodePtr basep, xmlNodePtr nodep, char *ns, char *local, int *cur, int index) /* {{{ */
+xmlNode *dom_get_elements_by_tag_name_ns_raw(xmlNodePtr basep, xmlNodePtr nodep, char *ns, char *local, zend_long *cur, zend_long index) /* {{{ */
 {
 	/* Can happen with detached document */
 	if (UNEXPECTED(nodep == NULL)) {
diff --git a/ext/dom/php_dom.h b/ext/dom/php_dom.h
index 86e6b131545..c5c888a64c5 100644
--- a/ext/dom/php_dom.h
+++ b/ext/dom/php_dom.h
@@ -88,7 +88,7 @@ typedef struct _dom_nnodemap_object {
 	xmlChar *ns;
 	php_libxml_cache_tag cache_tag;
 	dom_object *cached_obj;
-	int cached_obj_index;
+	zend_long cached_obj_index;
 	bool free_local : 1;
 	bool free_ns : 1;
 } dom_nnodemap_object;
@@ -133,7 +133,7 @@ void dom_reconcile_ns(xmlDocPtr doc, xmlNodePtr nodep);
 void dom_reconcile_ns_list(xmlDocPtr doc, xmlNodePtr nodep, xmlNodePtr last);
 xmlNsPtr dom_get_nsdecl(xmlNode *node, xmlChar *localName);
 void dom_normalize (xmlNodePtr nodep);
-xmlNode *dom_get_elements_by_tag_name_ns_raw(xmlNodePtr basep, xmlNodePtr nodep, char *ns, char *local, int *cur, int index);
+xmlNode *dom_get_elements_by_tag_name_ns_raw(xmlNodePtr basep, xmlNodePtr nodep, char *ns, char *local, zend_long *cur, zend_long index);
 void php_dom_create_implementation(zval *retval);
 int dom_hierarchy(xmlNodePtr parent, xmlNodePtr child);
 bool dom_has_feature(zend_string *feature, zend_string *version);
diff --git a/ext/dom/tests/gh15654.phpt b/ext/dom/tests/gh15654.phpt
new file mode 100644
index 00000000000..ed4b0f34aff
--- /dev/null
+++ b/ext/dom/tests/gh15654.phpt
@@ -0,0 +1,32 @@
+--TEST--
+GH-15654 (Signed integer overflow in ext/dom/nodelist.c)
+--EXTENSIONS--
+dom
+--SKIPIF--
+<?php
+if (PHP_INT_SIZE != 8) die('skip 64-bit only');
+?>
+--FILE--
+<?php
+define("MAX_64Bit", 9223372036854775807);
+define("MAX_32Bit", 2147483647);
+define("MIN_64Bit", -9223372036854775807 - 1);
+define("MIN_32Bit", -2147483647 - 1);
+$longVals = array(
+    0, MAX_64Bit, MIN_64Bit, MAX_32Bit, MIN_32Bit, MAX_64Bit - MAX_32Bit, MIN_64Bit - MIN_32Bit,
+);
+$dom = new DOMDocument;
+$dom->loadXML('<root><a/><b/><c/></root>');
+$children = $dom->documentElement->childNodes;
+foreach ($longVals as $value) {
+    var_dump($children[$value]?->nodeName);
+}
+?>
+--EXPECT--
+string(1) "a"
+NULL
+NULL
+NULL
+NULL
+NULL
+NULL