diff --git a/monitoring_prometheus/__manifest__.py b/monitoring_prometheus/__manifest__.py
index 22594d4..3fa7ae6 100644
--- a/monitoring_prometheus/__manifest__.py
+++ b/monitoring_prometheus/__manifest__.py
@@ -1,10 +1,11 @@
-# Copyright 2016-2019 Camptocamp SA
+# -*- coding: utf-8 -*-
+# Copyright 2016-2021 Camptocamp SA
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)
 
 
 {
     "name": "Monitoring: Prometheus Metrics",
-    "version": "13.0.1.0.0",
+    "version": "9.0.1.0.0",
     "author": "Camptocamp,Odoo Community Association (OCA)",
     "license": "AGPL-3",
     "category": "category",
diff --git a/monitoring_prometheus/controllers/prometheus_metrics.py b/monitoring_prometheus/controllers/prometheus_metrics.py
index 411a2ac..2aca0cc 100644
--- a/monitoring_prometheus/controllers/prometheus_metrics.py
+++ b/monitoring_prometheus/controllers/prometheus_metrics.py
@@ -1,8 +1,16 @@
+# -*- coding: utf-8 -*-
 # Copyright 2016-2021 Camptocamp SA
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)
+import logging
 
 from odoo.http import Controller, route
-from prometheus_client import generate_latest
+
+_logger = logging.getLogger(__name__)
+
+try:
+    from prometheus_client import generate_latest
+except (ImportError, IOError) as err:
+    _logger.warning(err)
 
 
 class PrometheusController(Controller):
diff --git a/monitoring_prometheus/models/ir_http.py b/monitoring_prometheus/models/ir_http.py
index 0c026d6..f610ef1 100644
--- a/monitoring_prometheus/models/ir_http.py
+++ b/monitoring_prometheus/models/ir_http.py
@@ -1,9 +1,17 @@
+# -*- coding: utf-8 -*-
 # Copyright 2016-2021 Camptocamp SA
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)
+import logging
 
 from odoo import models
 from odoo.http import request
-from prometheus_client import Summary, Counter
+
+_logger = logging.getLogger(__name__)
+
+try:
+    from prometheus_client import Summary, Counter
+except (ImportError, IOError) as err:
+    _logger.warning(err)
 
 
 REQUEST_TIME = Summary(
@@ -21,10 +29,10 @@ class IrHttp(models.AbstractModel):
 
         if path_info.startswith("/longpolling/"):
             LONGPOLLING_COUNT.inc()
-            return super()._dispatch()
+            return super(IrHttp, cls)._dispatch()
 
         if path_info.startswith("/metrics"):
-            return super()._dispatch()
+            return super(IrHttp, cls)._dispatch()
 
         if path_info.startswith("/web/static"):
             label = "assets"
@@ -35,6 +43,6 @@ class IrHttp(models.AbstractModel):
 
         res = None
         with REQUEST_TIME.labels(label).time():
-            res = super()._dispatch()
+            res = super(IrHttp, cls)._dispatch()
 
         return res