diff --git a/defaults/main.yml b/defaults/main.yml
index 244e2cf..4899b0e 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -14,6 +14,8 @@ prometheus_postgres_exporter_host: "/var/run/postgresql/"
 prometheus_postgres_exporter_sslmode: "disable"
 prometheus_postgres_exporter_user: "postgres"
 
+prometheus_retention_time: "15d"
+
 prometheus_server_enable: false
 prometheus_server_global_evaluation_interval: 15
 prometheus_server_global_scrape_interval: 15
diff --git a/tasks/prometheus.yml b/tasks/prometheus.yml
index ce8e69b..fb8ceae 100644
--- a/tasks/prometheus.yml
+++ b/tasks/prometheus.yml
@@ -50,6 +50,7 @@
     command:
       - '--config.file=/etc/prometheus/prometheus.yml'
       - '--storage.tsdb.path=/prometheus'
+      - '--storage.tsdb.retention.time={{ prometheus_retention_time }}'
       - '--web.console.libraries=/usr/share/prometheus/console_libraries'
       - '--web.console.templates=/usr/share/prometheus/consoles'
       - '--web.enable-admin-api'