diff --git a/pageserver/src/bin/pageserver.rs b/pageserver/src/bin/pageserver.rs
index ea360a5741..adefc1b6b5 100644
--- a/pageserver/src/bin/pageserver.rs
+++ b/pageserver/src/bin/pageserver.rs
@@ -88,7 +88,7 @@ impl CfgFileParams {
             None => DEFAULT_HTTP_LISTEN_ADDR.to_owned(),
         };
 
-        let checkpoint_distance: i128 = match self.checkpoint_distance.as_ref() {
+        let checkpoint_distance: u64 = match self.checkpoint_distance.as_ref() {
             Some(checkpoint_distance_str) => checkpoint_distance_str.parse()?,
             None => DEFAULT_CHECKPOINT_DISTANCE,
         };
diff --git a/pageserver/src/layered_repository.rs b/pageserver/src/layered_repository.rs
index c8a078c1c4..3d941fe7c0 100644
--- a/pageserver/src/layered_repository.rs
+++ b/pageserver/src/layered_repository.rs
@@ -1232,7 +1232,7 @@ impl LayeredTimeline {
     /// Flush to disk all data that was written with the put_* functions
     ///
     /// NOTE: This has nothing to do with checkpoint in PostgreSQL.
-    fn checkpoint_internal(&self, checkpoint_distance: i128) -> Result<()> {
+    fn checkpoint_internal(&self, checkpoint_distance: u64) -> Result<()> {
         // Grab lock on the layer map.
         //
         // TODO: We hold it locked throughout the checkpoint operation. That's bad,
@@ -1280,7 +1280,7 @@ impl LayeredTimeline {
             // inserted ourselves.
             let distance = last_record_lsn.widening_sub(oldest_pending_lsn);
             if distance < 0
-                || distance < checkpoint_distance
+                || distance < checkpoint_distance.into()
                 || oldest_generation == current_generation
             {
                 info!(
diff --git a/pageserver/src/lib.rs b/pageserver/src/lib.rs
index a1950c567f..d2dcdc427f 100644
--- a/pageserver/src/lib.rs
+++ b/pageserver/src/lib.rs
@@ -31,7 +31,7 @@ pub mod defaults {
     // FIXME: This current value is very low. I would imagine something like 1 GB or 10 GB
     // would be more appropriate. But a low value forces the code to be exercised more,
     // which is good for now to trigger bugs.
-    pub const DEFAULT_CHECKPOINT_DISTANCE: i128 = 64 * 1024 * 1024;
+    pub const DEFAULT_CHECKPOINT_DISTANCE: u64 = 64 * 1024 * 1024;
     pub const DEFAULT_CHECKPOINT_PERIOD: Duration = Duration::from_secs(100);
 
     pub const DEFAULT_GC_HORIZON: u64 = 64 * 1024 * 1024;
@@ -59,7 +59,7 @@ pub struct PageServerConf {
     // Flush out an inmemory layer, if it's holding WAL older than this
     // This puts a backstop on how much WAL needs to be re-digested if the
     // page server crashes.
-    pub checkpoint_distance: i128,
+    pub checkpoint_distance: u64,
     pub checkpoint_period: Duration,
 
     pub gc_horizon: u64,