diff --git a/installers/charm/osm-mon/src/charm.py b/installers/charm/osm-mon/src/charm.py
index ff111d6..f666bd5 100755
--- a/installers/charm/osm-mon/src/charm.py
+++ b/installers/charm/osm-mon/src/charm.py
@@ -239,7 +239,7 @@
             "OSMMON_DATABASE_COMMONKEY": self.config["database-commonkey"],
             # Prometheus/grafana configuration
             "OSMMON_PROMETHEUS_URL": f"http://{self.prometheus_client.hostname}:{self.prometheus_client.port}",
-            "OSMMON_PROMETHEUS_USER": self.prometheus_client.user
+            "OSMMON_PROMETHEUS_USER": self.prometheus_client.user,
             "OSMMON_PROMETHEUS_PASSWORD": self.prometheus_client.password,
             "OSMMON_GRAFANA_URL": self.config["grafana-url"],
             "OSMMON_GRAFANA_USER": self.config["grafana-user"],