diff --git a/ext/dom/document.c b/ext/dom/document.c
index e48cafbabe9..faf6e210e2d 100644
--- a/ext/dom/document.c
+++ b/ext/dom/document.c
@@ -1234,7 +1234,7 @@ PHP_METHOD(DOMDocument, __construct)
 	}
 
 	if (encoding_len > 0) {
-		docp->encoding = (const xmlChar *) xmlStrdup((xmlChar *) encoding);
+		docp->encoding = xmlStrdup((const xmlChar *) encoding);
 	}
 
 	intern = Z_DOMOBJ_P(ZEND_THIS);