diff --git a/prometheus/DOCS.md b/prometheus/DOCS.md
index eac664a..db78f2d 100644
--- a/prometheus/DOCS.md
+++ b/prometheus/DOCS.md
@@ -17,7 +17,10 @@ comparison to installing any other Home Assistant add-on.
 
 ## Configuration
 
-There are no configuration options for the addon.
+### Option: `retention_days`
+
+Specify when to remove old data.
+
 
 To add additional scrape targets you need to create a file per target in /share/prometheus/targets.
 
diff --git a/prometheus/config.json b/prometheus/config.json
index 5c2c647..3d5f4c9 100755
--- a/prometheus/config.json
+++ b/prometheus/config.json
@@ -19,5 +19,11 @@
   },
   "ports_description": {
     "9090/tcp": "Not required for Ingress"
+  },
+  "schema": {
+    "retention_days": "int"
+  },
+  "options": {
+    "retention_days": 15
   }
 }
diff --git a/prometheus/rootfs/etc/services.d/prometheus/run b/prometheus/rootfs/etc/services.d/prometheus/run
index deb569a..ce316f8 100755
--- a/prometheus/rootfs/etc/services.d/prometheus/run
+++ b/prometheus/rootfs/etc/services.d/prometheus/run
@@ -12,6 +12,7 @@ bashio::log.info 'Starting prometheus...'
 
 options+=(--config.file="/etc/prometheus/prometheus.yml" )
 options+=(--storage.tsdb.path="/data/prometheus" )
+options+=(--storage.tsdb.retention.time=$(bashio::config 'retention_days')d)
 options+=(--web.console.libraries="/usr/share/prometheus/console_libraries" )
 options+=(--web.console.templates="/usr/share/prometheus/consoles" )
 options+=(--web.route-prefix="/" )