diff --git a/ext/ldap/tests/gh17704.phpt b/ext/ldap/tests/gh17704.phpt
new file mode 100644
index 0000000000000..2403a63860e4a
--- /dev/null
+++ b/ext/ldap/tests/gh17704.phpt
@@ -0,0 +1,24 @@
+--TEST--
+GH-17704 (ldap_search fails when $attributes contains a non-packed array with numerical keys)
+--EXTENSIONS--
+ldap
+--SKIPIF--
+<?php
+require_once('skipifbindfailure.inc');
+?>
+--FILE--
+<?php
+include "connect.inc";
+
+$link = ldap_connect_and_bind($uri, $user, $passwd, $protocol_version);
+
+$attributes = ["uid", "cn"];
+// force a non-packed array
+$attributes["x"] = "x";
+unset($attributes["x"]);
+
+var_dump(ldap_search($link, $base, "(o=*)", $attributes));
+?>
+--EXPECTF--
+object(LDAP\Result)#%d (0) {
+}