diff --git a/contrib/cortexutils/extractor.py b/contrib/cortexutils/extractor.py
index f77c1df13..264e5ad12 100644
--- a/contrib/cortexutils/extractor.py
+++ b/contrib/cortexutils/extractor.py
@@ -28,7 +28,7 @@ def __init_regex():
         # IPv4
         regex = [{
             'type': 'ip',
-            'regex': re.compile(r'[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}')
+            'regex': re.compile(r'^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?:\/\d\d?)?$')
         }]
 
         # IPv6