diff --git a/machines/fuuko/services/prometheus.nix b/machines/fuuko/services/prometheus.nix
index 55e8387..0351c30 100644
--- a/machines/fuuko/services/prometheus.nix
+++ b/machines/fuuko/services/prometheus.nix
@@ -23,6 +23,9 @@ in
       scrape_interval = "15s";
       evaluation_interval = "15s";
     };
+    extraFlags = [
+      "--storage.tsdb.retention.time=90d"
+    ];
 
     alertmanagers = [
       { static_configs = mkStaticTarget "${cfg.alertmanager.listenAddress}:${toString cfg.alertmanager.port}"; }