diff --git a/dict.c b/dict.c
index 2dd759d..aa29976 100644
--- a/dict.c
+++ b/dict.c
@@ -256,7 +256,7 @@
  * xmlDictLookup:
  * @dict: the dictionnary
  * @name: the name of the userdata
- * @len: the length of the name
+ * @len: the length of the name, if -1 it is recomputed
  *
  * Add the @name to the hash @dict if not present.
  *
@@ -269,7 +269,12 @@
     xmlDictEntryPtr insert;
     const xmlChar *ret;
 
-    if ((dict == NULL) || (name == NULL) || (len <= 0))
+    if ((dict == NULL) || (name == NULL))
+	return(NULL);
+
+    if (len < 0)
+        len = xmlStrlen(name);
+    if (len <= 0)
 	return(NULL);
 
     /*