diff --git a/semgr8s/k8s_api.py b/semgr8s/k8s_api.py
index a21d071..e466f1e 100644
--- a/semgr8s/k8s_api.py
+++ b/semgr8s/k8s_api.py
@@ -28,7 +28,7 @@ def request_kube_api(path: str):
     try:
         response = requests.get(url, verify=ca_path, headers=headers, timeout=30)
     except JSONDecodeError as err:
-        APP.logger.error("ERROR: Malformed k8s API response or resource yaml: %s", err)
+        APP.logger.error("Malformed k8s API response or resource yaml: %s", err)
         return {}
 
     response.raise_for_status()
diff --git a/semgr8s/updater.py b/semgr8s/updater.py
index 4297219..09a5b58 100644
--- a/semgr8s/updater.py
+++ b/semgr8s/updater.py
@@ -2,21 +2,28 @@
 Update cached rules from configmaps.
 """
 
-import logging
 import os
 
 from urllib.parse import urlencode
 
 from semgr8s.k8s_api import request_kube_api
+from semgr8s.app import APP
+
+RULESPATH = "/app/rules"
 
 
 def update_rules():
     """
     Request all rule configmaps from kubernetes api and store locally in semgrep format.
     """
-    logging.info("INFO: updateing rule set")
+    APP.logger.debug("Updating rule set")
 
     try:
+        old_rule_files = [
+            file
+            for file in os.listdir(RULESPATH)
+            if os.path.isfile(os.path.join(RULESPATH, file))
+        ]
         namespace = os.getenv("NAMESPACE", "default")
         query = {"labelSelector": "semgr8s/rule"}
 
@@ -28,8 +35,16 @@ def update_rules():
             data = list(item.get("data", {}).items())
             for datum in data:
                 file, content = datum
-                with open(f"/app/rules/{file}", "w", encoding="utf-8") as rule_file:
+                path = os.path.join(RULESPATH, file)
+                with open(path, "w", encoding="utf-8") as rule_file:
                     rule_file.write(content)
-                logging.info("INFO: updated %s rule", file)
+                APP.logger.debug("Updated %s rule", file)
+                try:
+                    old_rule_files.remove(file)
+                except ValueError:
+                    pass
+        for deprecated_rule in old_rule_files:
+            os.remove(os.path.join(RULESPATH, deprecated_rule))
+            APP.logger.info("Deleted %s rule", deprecated_rule)
     except Exception as err:  # pylint: disable=W0718
-        logging.error("Error updating rules: %s", err)
+        APP.logger.error("Updating rules failed unexpectedly: %s", err)