diff --git a/ext/soap/php_schema.c b/ext/soap/php_schema.c
index f1af0110bab..dc6816034de 100644
--- a/ext/soap/php_schema.c
+++ b/ext/soap/php_schema.c
@@ -48,6 +48,7 @@ static bool node_is_equal_xsd(xmlNodePtr node, const char *name)
 	static const char *ns[] = {
 		XSD_NAMESPACE,
 		XSD_DRAFT_2000_NAMESPACE,
+		XSD_1999_NAMESPACE,
 		NULL
 	};