diff --git a/tree.c b/tree.c
index fe57921..432007e 100644
--- a/tree.c
+++ b/tree.c
@@ -4848,7 +4848,7 @@
     fixed = xmlPathToURI(uri);
     if (fixed != NULL) {
 	xmlSetNsProp(cur, ns, BAD_CAST "base", fixed);
-	xmlFree(fixed);
+	xmlFree((xmlChar *)fixed);
     } else {
 	xmlSetNsProp(cur, ns, BAD_CAST "base", uri);
     }