diff --git a/libs/pageserver_api/src/models.rs b/libs/pageserver_api/src/models.rs
index 4b6b01124a..2b220001e7 100644
--- a/libs/pageserver_api/src/models.rs
+++ b/libs/pageserver_api/src/models.rs
@@ -248,7 +248,7 @@ pub enum LayerAccessKind {
 }
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct LayerAccessStatFullDetails {
-    pub when_millis_since_epoch: u128,
+    pub when_millis_since_epoch: u64,
     pub task_kind: &'static str,
     pub access_kind: LayerAccessKind,
 }
@@ -257,11 +257,11 @@ pub struct LayerAccessStatFullDetails {
 #[serde(tag = "kind")]
 pub enum LayerResidenceStatus {
     Resident {
-        timestamp_millis_since_epoch: u128,
+        timestamp_millis_since_epoch: u64,
         created: bool,
     },
     Evicted {
-        timestamp_millis_since_epoch: u128,
+        timestamp_millis_since_epoch: u64,
     },
 }
 
diff --git a/pageserver/src/tenant/storage_layer.rs b/pageserver/src/tenant/storage_layer.rs
index e155303e57..ea2bd9e328 100644
--- a/pageserver/src/tenant/storage_layer.rs
+++ b/pageserver/src/tenant/storage_layer.rs
@@ -125,10 +125,12 @@ pub enum LayerAccessStatsReset {
     AllStats,
 }
 
-fn system_time_to_millis_since_epoch(ts: &SystemTime) -> u128 {
+fn system_time_to_millis_since_epoch(ts: &SystemTime) -> u64 {
     ts.duration_since(UNIX_EPOCH)
         .expect("better to die in this unlikely case than report false stats")
         .as_millis()
+        .try_into()
+        .expect("64 bits is enough for few more years")
 }
 
 impl LayerAccessStatFullDetails {