diff --git a/waf/modsecurity.py b/waf/modsecurity.py
index 6827d6945..d1d995452 100644
--- a/waf/modsecurity.py
+++ b/waf/modsecurity.py
@@ -19,6 +19,7 @@ def detect(get_page):
         page, headers, code = get_page(get=vector)
         retval = code == 501 and re.search(r"Reference #[0-9A-Fa-f.]+", page, re.I) is None
         retval |= re.search(r"Mod_Security|NOYB", headers.get(HTTP_HEADER.SERVER, ""), re.I) is not None
+        retval |= "This error was generated by Mod_Security" in page
         if retval:
             break