diff --git a/rust/lancedb/src/table/dataset.rs b/rust/lancedb/src/table/dataset.rs
index 2dd3b7189..e37c3fc9f 100644
--- a/rust/lancedb/src/table/dataset.rs
+++ b/rust/lancedb/src/table/dataset.rs
@@ -518,6 +518,10 @@ mod tests {
 
         let wrapper = DatasetConsistencyWrapper::new_latest(ds, Some(Duration::from_millis(200)));
 
+        // Freeze `cached_at` on the mock clock so a slow external write below can't
+        // expire the TTL before the explicit advance_by() does (flake on loaded CI).
+        clock::pin();
+
         // Populate the cache
         let v1 = wrapper.get().await.unwrap().version().version;
         assert_eq!(v1, 1);
diff --git a/rust/lancedb/src/utils/background_cache.rs b/rust/lancedb/src/utils/background_cache.rs
index bdf033fec..e493fd4c6 100644
--- a/rust/lancedb/src/utils/background_cache.rs
+++ b/rust/lancedb/src/utils/background_cache.rs
@@ -329,6 +329,15 @@ pub mod clock {
         });
     }
 
+    /// Start mock time at the current instant if not already pinned.
+    pub fn pin() {
+        MOCK_NOW.with(|mock| {
+            if mock.get().is_none() {
+                mock.set(Some(Instant::now()));
+            }
+        });
+    }
+
     #[allow(dead_code)]
     pub fn clear_mock() {
         MOCK_NOW.with(|mock| mock.set(None));