diff --git a/uri.c b/uri.c
index 15cb92b37..14ad94eca 100644
--- a/uri.c
+++ b/uri.c
@@ -1644,6 +1644,8 @@ xmlURIEscapeStr(const xmlChar *str, const xmlChar *list) {
     if (str[0] == 0)
 	return(xmlStrdup(str));
     len = xmlStrlen(str);
+    if (len == 0)
+        return(NULL);
 
     len += 20;
     ret = xmlMalloc(len);