diff --git a/docs/content/howto/monitoring-with-prometheus-and-grafana/index.md b/docs/content/howto/monitoring-with-prometheus-and-grafana/index.md
index 7c913c0..4588e0e 100644
--- a/docs/content/howto/monitoring-with-prometheus-and-grafana/index.md
+++ b/docs/content/howto/monitoring-with-prometheus-and-grafana/index.md
@@ -3,7 +3,10 @@ title: "Monitoring iocaine"
 description: How to monitor iocaine with Prometheus and Grafana?
 ---
 
-`iocaine` can be [configured](@/configuration/index.md#metrics) to expose [Prometheus](https://prometheus.io)-compatible metrics, separately from the garbage generator. When enabled, a single metric - `iocaine_requests_total` - is exposed, with various labels attached, if so configured. It is a simple counter, showing the number of hits `iocaine` served.
+`iocaine` can be [configured](@/configuration/index.md#metrics) to expose [Prometheus](https://prometheus.io)-compatible metrics, separately from the garbage generator. When enabled, two metrics are exposed:
+
+- `iocaine_requests_total`, a counter of how many hits `iocaine` served, optionally with labels attached (see below).
+- `process_start_time_seconds`, a gauge, a timestamp of when `iocaine` started, to allow measuring uptime.
 
 # The simplest configuration
 
@@ -14,13 +17,18 @@ Lets start with a simple configuration: no labels, just the metric.
 enable = true
 ```
 
-This will expose the following metric on `http://127.0.0.1:42042/metrics`:
+This will expose the following metrics on `http://127.0.0.1:42042/metrics`:
 
 ```
 # TYPE iocaine_requests_total counter
 iocaine_requests_total 1
+
+# TYPE process_start_time_seconds gauge
+process_start_time_seconds{instance="127.0.0.1:42042",service="iocaine"} 1738873005.2406795
 ```
 
+The `process_start_time_seconds` metric is *always* present, and its value only changes when `iocaine` is restarted. For the sake of brevity, it is excluded from all other examples.
+
 # Per-host metrics
 
 While an unlabeled metric is nice to have, it's a little bit bland. We can add a `host` label, to be able to group request totals by host - where the host is whatever is in the `Host` header when it reaches `iocaine`.
diff --git a/src/app.rs b/src/app.rs
index 28de060..4a305ed 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -19,6 +19,8 @@ use axum::{
 #[cfg(feature = "prometheus")]
 use metrics_exporter_prometheus::{PrometheusBuilder, PrometheusHandle};
 use std::sync::Arc;
+#[cfg(feature = "prometheus")]
+use std::time::{SystemTime, UNIX_EPOCH};
 
 #[cfg(feature = "prometheus")]
 use crate::config::MetricsLabel;
@@ -160,9 +162,18 @@ impl Iocaine {
 
     #[cfg(feature = "prometheus")]
     async fn start_metrics_server(metrics_bind: String) -> std::result::Result<(), std::io::Error> {
-        let metrics_listener = tokio::net::TcpListener::bind(metrics_bind).await?;
+        let metrics_listener = tokio::net::TcpListener::bind(metrics_bind.clone()).await?;
         let app = Self::metrics_app().await;
 
+        let ts = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .expect("Time went backwards");
+        let labels = [
+            ("instance", metrics_bind),
+            ("service", "iocaine".to_string()),
+        ];
+        metrics::gauge!("process_start_time_seconds", &labels).set(ts);
+
         axum::serve(metrics_listener, app)
             .with_graceful_shutdown(shutdown_signal())
             .await