diff --git a/api/src/dav/locks.rs b/api/src/dav/locks.rs
index d59fd41..215cc32 100644
--- a/api/src/dav/locks.rs
+++ b/api/src/dav/locks.rs
@@ -334,14 +334,18 @@ mod tests {
 
     #[test]
     fn an_etag_condition_is_not_mistaken_for_a_token() {
-        assert!(submitted_tokens(Some(r#"(["etag-value"])"#)).is_empty());
-        assert!(submitted_tokens(Some("(<urn:something-else>)")).is_empty());
+        let tokens = submitted_tokens(Some(r#"(["etag-value"])"#));
+        assert!(tokens.is_empty(), "{tokens:?}");
+        let tokens = submitted_tokens(Some("(<urn:something-else>)"));
+        assert!(tokens.is_empty(), "{tokens:?}");
     }
 
     #[test]
     fn nothing_submitted_is_no_tokens_rather_than_a_failure() {
-        assert!(submitted_tokens(None).is_empty());
-        assert!(submitted_tokens(Some("garbage <unclosed")).is_empty());
+        let tokens = submitted_tokens(None);
+        assert!(tokens.is_empty(), "{tokens:?}");
+        let tokens = submitted_tokens(Some("garbage <unclosed"));
+        assert!(tokens.is_empty(), "{tokens:?}");
     }
 
     #[test]
diff --git a/api/src/dav/mod.rs b/api/src/dav/mod.rs
index a05a835..977f330 100644
--- a/api/src/dav/mod.rs
+++ b/api/src/dav/mod.rs
@@ -101,7 +101,8 @@ mod tests {
     fn the_collection_at_the_root_is_an_empty_path() {
         for raw in ["/dav", "/dav/"] {
             let uri: axum::http::Uri = raw.parse().expect("a valid uri");
-            assert!(path_of(&uri).expect("a valid path").is_empty());
+            let path = path_of(&uri).expect("a valid path");
+            assert!(path.is_empty(), "{path:?}");
         }
     }
 
diff --git a/api/src/dav/propfind.rs b/api/src/dav/propfind.rs
index eb2ba31..7d5ec9c 100644
--- a/api/src/dav/propfind.rs
+++ b/api/src/dav/propfind.rs
@@ -140,7 +140,7 @@ mod tests {
             requested.properties,
             vec![Property::Etag, Property::ContentLength]
         );
-        assert!(requested.unknown.is_empty());
+        assert!(requested.unknown.is_empty(), "{:?}", requested.unknown);
     }
 
     #[test]
@@ -168,7 +168,11 @@ mod tests {
             br#"<D:propfind xmlns:D="DAV:" xmlns:Z="urn:example:"><D:prop><Z:getetag/></D:prop></D:propfind>"#,
         );
 
-        assert!(requested.properties.is_empty());
+        assert!(
+            requested.properties.is_empty(),
+            "{:?}",
+            requested.properties
+        );
         assert_eq!(requested.unknown, vec![unknown("urn:example:", "getetag")]);
     }
 
diff --git a/api/src/storage/tests.rs b/api/src/storage/tests.rs
index 7759acf..047a7e4 100644
--- a/api/src/storage/tests.rs
+++ b/api/src/storage/tests.rs
@@ -492,7 +492,8 @@ async fn an_object_store_sweeps_a_staging_object_nobody_placed() {
         .expect("sweep");
 
     assert_eq!(cleared, 1);
-    assert!(fixture.keys().await.is_empty());
+    let keys = fixture.keys().await;
+    assert!(keys.is_empty(), "{keys:?}");
 }
 
 #[test]
diff --git a/api/tests/client.rs b/api/tests/client.rs
index 8b0234b..fe0a81b 100644
--- a/api/tests/client.rs
+++ b/api/tests/client.rs
@@ -54,7 +54,8 @@ database_test!(the_client_restores_and_purges_from_the_trash, harness, {
     remote.purge(gone.id).await.expect("purging");
 
     assert_eq!(restored.name, "back.txt");
-    assert!(harness.trashed(owner.id).await.is_empty());
+    let trashed = harness.trashed(owner.id).await;
+    assert!(trashed.is_empty(), "{trashed:?}");
     assert_eq!(harness.resolve(owner.id, "back.txt").await.id, back.id);
 });
 
@@ -105,7 +106,8 @@ database_test!(the_client_empties_the_trash, harness, {
 
     remote.empty_trash().await.expect("emptying");
 
-    assert!(harness.trashed(owner.id).await.is_empty());
+    let trashed = harness.trashed(owner.id).await;
+    assert!(trashed.is_empty(), "{trashed:?}");
 });
 
 database_test!(the_client_lists_downloads_and_restores_versions, harness, {
diff --git a/api/tests/dav.rs b/api/tests/dav.rs
index 6119ecb..44139bb 100644
--- a/api/tests/dav.rs
+++ b/api/tests/dav.rs
@@ -334,7 +334,8 @@ database_test!(delete_moves_a_node_to_the_trash, harness, {
 
     assert_eq!(answer.status, StatusCode::NO_CONTENT);
     let root = harness.root(owner).await;
-    assert!(harness.children(&root).await.is_empty());
+    let children = harness.children(&root).await;
+    assert!(children.is_empty(), "{children:?}");
     assert_eq!(harness.trashed(owner).await, ["photos"]);
 });
 
diff --git a/api/tests/grants.rs b/api/tests/grants.rs
index 895a37c..b9362bf 100644
--- a/api/tests/grants.rs
+++ b/api/tests/grants.rs
@@ -287,7 +287,8 @@ database_test!(
         .await;
         assert_eq!(deleted.status, StatusCode::NO_CONTENT);
         assert_eq!(harness.trashed(owner).await, ["new.txt"]);
-        assert!(harness.trashed(guest_id).await.is_empty());
+        let trashed = harness.trashed(guest_id).await;
+        assert!(trashed.is_empty(), "{trashed:?}");
     }
 );
 
@@ -594,12 +595,8 @@ database_test!(a_revoked_grant_is_gone_on_the_next_request, harness, {
         get(&harness, path, &guest).await.status,
         StatusCode::NOT_FOUND
     );
-    assert!(
-        get(&harness, "/v1/folders", &guest)
-            .await
-            .names()
-            .is_empty()
-    );
+    let names = get(&harness, "/v1/folders", &guest).await.names();
+    assert!(names.is_empty(), "{names:?}");
 });
 
 database_test!(
@@ -976,7 +973,8 @@ database_test!(a_write_grant_on_a_file_grows_nothing_below_it, harness, {
     .await;
 
     assert_eq!(written.status, StatusCode::BAD_REQUEST, "{}", written.body);
-    assert!(harness.children(&file).await.is_empty());
+    let children = harness.children(&file).await;
+    assert!(children.is_empty(), "{children:?}");
     assert_eq!(
         overwritten.status,
         StatusCode::CREATED,
diff --git a/api/tests/routes.rs b/api/tests/routes.rs
index 87e2726..ac6376a 100644
--- a/api/tests/routes.rs
+++ b/api/tests/routes.rs
@@ -337,7 +337,8 @@ database_test!(a_purge_answers_no_content, harness, {
     .await;
 
     assert_eq!(status, StatusCode::NO_CONTENT);
-    assert!(harness.trashed(member.id).await.is_empty());
+    let trashed = harness.trashed(member.id).await;
+    assert!(trashed.is_empty(), "{trashed:?}");
 });
 
 database_test!(a_reader_may_not_restore, harness, {
diff --git a/api/tests/storage.rs b/api/tests/storage.rs
index a1a3ac5..d12cf71 100644
--- a/api/tests/storage.rs
+++ b/api/tests/storage.rs
@@ -246,7 +246,8 @@ database_test!(a_move_carries_the_subtree_with_it, harness, {
         "the child came along"
     );
     let inbox = harness.resolve(owner.id, "inbox").await;
-    assert!(harness.children(&inbox).await.is_empty());
+    let children = harness.children(&inbox).await;
+    assert!(children.is_empty(), "{children:?}");
 });
 
 database_test!(a_directory_cannot_be_moved_inside_itself, harness, {
@@ -466,7 +467,8 @@ database_test!(trashing_a_directory_takes_its_whole_subtree, harness, {
     harness.trash(&photos).await;
 
     let root = harness.root(owner.id).await;
-    assert!(harness.children(&root).await.is_empty());
+    let children = harness.children(&root).await;
+    assert!(children.is_empty(), "{children:?}");
     assert_eq!(
         harness.live_nodes(owner.id).await,
         0,
@@ -696,7 +698,8 @@ database_test!(purging_leaves_nothing_to_restore, harness, {
 
     harness.purge(owner.id, node.id).await;
 
-    assert!(harness.trashed(owner.id).await.is_empty());
+    let trashed = harness.trashed(owner.id).await;
+    assert!(trashed.is_empty(), "{trashed:?}");
     assert!(
         matches!(
             harness.try_restore(owner.id, node.id).await,
@@ -771,6 +774,7 @@ database_test!(
             Some((0, true)),
             "the row went with the parent, so its reference has to go too"
         );
-        assert!(harness.trashed(owner.id).await.is_empty());
+        let trashed = harness.trashed(owner.id).await;
+        assert!(trashed.is_empty(), "{trashed:?}");
     }
 );
diff --git a/api/tests/trash.rs b/api/tests/trash.rs
index bdc6e0b..13d280c 100644
--- a/api/tests/trash.rs
+++ b/api/tests/trash.rs
@@ -80,7 +80,8 @@ database_test!(
 
         assert_eq!(empty(&harness, owner.id).await, 2);
 
-        assert!(harness.trashed(owner.id).await.is_empty());
+        let trashed = harness.trashed(owner.id).await;
+        assert!(trashed.is_empty(), "{trashed:?}");
         assert_eq!(harness.trashed(neighbour.id).await, ["x.txt"]);
         assert_eq!(harness.resolve(owner.id, "keep.txt").await.name, "keep.txt");
         for contents in [&b"deleted file"[..], b"deleted with its folder"] {
@@ -112,7 +113,8 @@ database_test!(
 
         empty(&harness, owner.id).await;
 
-        assert!(harness.trashed(owner.id).await.is_empty());
+        let trashed = harness.trashed(owner.id).await;
+        assert!(trashed.is_empty(), "{trashed:?}");
         for contents in [&b"deleted first"[..], b"deleted with the folder"] {
             assert_eq!(harness.blob(hash_of(contents)).await, Some((0, true)));
         }
@@ -174,7 +176,8 @@ database_test!(
             .await
             .expect("an entry already purged with its folder is skipped, not an error");
 
-        assert!(harness.trashed(owner.id).await.is_empty());
+        let trashed = harness.trashed(owner.id).await;
+        assert!(trashed.is_empty(), "{trashed:?}");
     }
 );
 
diff --git a/crates/client/src/sync/held.rs b/crates/client/src/sync/held.rs
index 2169309..dbac22d 100644
--- a/crates/client/src/sync/held.rs
+++ b/crates/client/src/sync/held.rs
@@ -234,7 +234,7 @@ mod tests {
         };
         let plan = outcome(conflict.clone());
         assert_eq!(plan.actions, [conflict]);
-        assert!(plan.held.is_empty());
+        assert!(plan.held.is_empty(), "{:?}", plan.held);
     }
 
     #[test]
diff --git a/crates/client/src/sync/plan.rs b/crates/client/src/sync/plan.rs
index 25b0dfe..886663f 100644
--- a/crates/client/src/sync/plan.rs
+++ b/crates/client/src/sync/plan.rs
@@ -519,7 +519,7 @@ mod tests {
         let remote = snapshot(&[("a", Entry::Directory)]);
 
         let plan = reconcile(&local, &remote, &Snapshot::new(), now());
-        assert!(plan.actions.is_empty());
+        assert!(plan.actions.is_empty(), "{:?}", plan.actions);
         assert_eq!(plan.blocked, [at("a")]);
     }
 }
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 0ca8f70..3130dd8 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,4 +1,4 @@
 [toolchain]
-channel = "1.98"
+channel = "1.99"
 components = ["rustfmt", "clippy"]
 profile = "minimal"