diff --git a/src/lib.rs b/src/lib.rs
index aed3524..e8c6eed 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -12,6 +12,8 @@
 //! details.
 
 #![cfg_attr(feature = "bench", feature(test))]
+// This would add is_empty() functions to public traits
+#![allow(clippy::len_without_is_empty)]
 
 #[macro_use]
 extern crate log;
diff --git a/src/snapshot_vec.rs b/src/snapshot_vec.rs
index efde49a..90f461f 100644
--- a/src/snapshot_vec.rs
+++ b/src/snapshot_vec.rs
@@ -165,10 +165,10 @@ impl<D: SnapshotVecDelegate, V: VecLike<D> + Default, L: Default> SnapshotVec<D,
 
 impl<D: SnapshotVecDelegate> SnapshotVecStorage<D> {
     /// Creates a `SnapshotVec` using the `undo_log`, allowing mutating methods to be called
-    pub fn with_log<'a, L>(
-        &'a mut self,
+    pub fn with_log<L>(
+        &mut self,
         undo_log: L,
-    ) -> SnapshotVec<D, &'a mut Vec<<D as SnapshotVecDelegate>::Value>, L>
+    ) -> SnapshotVec<D, &mut Vec<<D as SnapshotVecDelegate>::Value>, L>
     where
         L: UndoLogs<UndoLog<D>>,
     {
diff --git a/src/undo_log.rs b/src/undo_log.rs
index 0d6d2f6..839b767 100644
--- a/src/undo_log.rs
+++ b/src/undo_log.rs
@@ -40,7 +40,7 @@ pub trait UndoLogs<T> {
     }
 }
 
-impl<'a, T, U> UndoLogs<T> for &'a mut U
+impl<T, U> UndoLogs<T> for &mut U
 where
     U: UndoLogs<T>,
 {
diff --git a/src/unify/mod.rs b/src/unify/mod.rs
index 41c9d46..44fc668 100644
--- a/src/unify/mod.rs
+++ b/src/unify/mod.rs
@@ -211,9 +211,9 @@ impl<K: UnifyKey> VarValue<K> {
 
     fn new(parent: K, value: K::Value, rank: u32) -> VarValue<K> {
         VarValue {
-            parent: parent, // this is a root
-            value: value,
-            rank: rank,
+            parent, // this is a root
+            value,
+            rank,
         }
     }
 
@@ -233,10 +233,10 @@ where
 {
     /// Creates a `UnificationTable` using an external `undo_log`, allowing mutating methods to be
     /// called if `L` does not implement `UndoLogs`
-    pub fn with_log<'a, L>(
-        &'a mut self,
+    pub fn with_log<L>(
+        &mut self,
         undo_log: L,
-    ) -> UnificationTable<InPlace<K, &'a mut UnificationStorage<K>, L>>
+    ) -> UnificationTable<InPlace<K, &mut UnificationStorage<K>, L>>
     where
         L: UndoLogs<sv::UndoLog<Delegate<K>>>,
     {
@@ -324,7 +324,7 @@ impl<S: UnificationStoreMut> UnificationTable<S> {
     /// the closure.
     pub fn reset_unifications(&mut self, mut value: impl FnMut(S::Key) -> S::Value) {
         self.values.reset_unifications(|i| {
-            let key = UnifyKey::from_index(i as u32);
+            let key = UnifyKey::from_index(i);
             let value = value(key);
             VarValue::new_var(key, value)
         });
@@ -443,8 +443,7 @@ impl<S: UnificationStoreMut> UnificationTable<S> {
     }
 }
 
-/// ////////////////////////////////////////////////////////////////////////
-/// Public API
+// Public API
 
 impl<S, K, V> UnificationTable<S>
 where
@@ -535,7 +534,8 @@ where
 
         let combined = V::unify_values(&self.value(root_a).value, &self.value(root_b).value)?;
 
-        Ok(self.unify_roots(root_a, root_b, combined))
+        self.unify_roots(root_a, root_b, combined);
+        Ok(())
     }
 
     /// Sets the value of the key `a_id` to `b`, attempting to merge
@@ -587,9 +587,9 @@ impl<V: UnifyValue> UnifyValue for Option<V> {
 
     fn unify_values(a: &Option<V>, b: &Option<V>) -> Result<Self, V::Error> {
         match (a, b) {
-            (&None, &None) => Ok(None),
-            (&Some(ref v), &None) | (&None, &Some(ref v)) => Ok(Some(v.clone())),
-            (&Some(ref a), &Some(ref b)) => match V::unify_values(a, b) {
+            (None, None) => Ok(None),
+            (Some(v), None) | (None, Some(v)) => Ok(Some(v.clone())),
+            (Some(a), Some(b)) => match V::unify_values(a, b) {
                 Ok(v) => Ok(Some(v)),
                 Err(err) => Err(err),
             },
diff --git a/src/unify/tests.rs b/src/unify/tests.rs
index 5665aba..04c1cc9 100644
--- a/src/unify/tests.rs
+++ b/src/unify/tests.rs
@@ -40,6 +40,8 @@ impl UnifyKey for UnitKey {
 
 macro_rules! all_modes {
     ($name:ident for $t:ty => $body:tt) => {
+        // The $name field is only needed by some callers
+        #[allow(clippy::extra_unused_type_parameters)]
         fn test_body<
             $name: Clone + Default + UnificationStore<Key = $t, Value = <$t as UnifyKey>::Value>,
         >() {
@@ -60,9 +62,9 @@ fn basic() {
             let mut ut: UnificationTable<S> = UnificationTable::new();
             let k1 = ut.new_key(());
             let k2 = ut.new_key(());
-            assert_eq!(ut.unioned(k1, k2), false);
+            assert!(!ut.unioned(k1, k2));
             ut.union(k1, k2);
-            assert_eq!(ut.unioned(k1, k2), true);
+            assert!(ut.unioned(k1, k2));
         }
     }
 }
@@ -386,12 +388,10 @@ impl UnifyKey for OrderedKey {
         b_rank: &OrderedRank,
     ) -> Option<(OrderedKey, OrderedKey)> {
         println!("{:?} vs {:?}", a_rank, b_rank);
-        if a_rank > b_rank {
-            Some((a, b))
-        } else if b_rank > a_rank {
-            Some((b, a))
-        } else {
-            None
+        match a_rank.cmp(b_rank) {
+            cmp::Ordering::Greater => Some((a, b)),
+            cmp::Ordering::Less => Some((b, a)),
+            cmp::Ordering::Equal => None,
         }
     }
 }
@@ -424,7 +424,7 @@ fn ordered_key() {
             ut.union(k0_5, k0_6); // rank of new root now 1
 
             ut.union(k0_1, k0_5); // new root rank 2, should not be k0_5 or k0_6
-            assert!(vec![k0_1, k0_2, k0_3, k0_4].contains(&ut.find(k0_1)));
+            assert!([k0_1, k0_2, k0_3, k0_4].contains(&ut.find(k0_1)));
         }
     }
 }
@@ -450,7 +450,7 @@ fn ordered_key_k1() {
 
             ut.union(k0_1, k1_5); // even though k1 has lower rank, it wins
             assert!(
-                vec![k1_5, k1_6].contains(&ut.find(k0_1)),
+                [k1_5, k1_6].contains(&ut.find(k0_1)),
                 "unexpected choice for root: {:?}",
                 ut.find(k0_1)
             );
diff --git a/tests/external_undo_log.rs b/tests/external_undo_log.rs
index 2537826..ff2164a 100644
--- a/tests/external_undo_log.rs
+++ b/tests/external_undo_log.rs
@@ -80,7 +80,7 @@ struct TypeVariableTable<'a> {
 }
 
 impl TypeVariableTable<'_> {
-    fn new(&mut self, i: i32) -> IntKey {
+    fn new_key(&mut self, i: i32) -> IntKey {
         self.storage.values.with_log(&mut self.undo_log).push(i);
         self.storage
             .eq_relations
@@ -93,20 +93,12 @@ struct Snapshot {
     undo_len: usize,
 }
 
+#[derive(Default)]
 struct TypeVariableUndoLogs {
     logs: Vec<UndoLog>,
     num_open_snapshots: usize,
 }
 
-impl Default for TypeVariableUndoLogs {
-    fn default() -> Self {
-        Self {
-            logs: Default::default(),
-            num_open_snapshots: Default::default(),
-        }
-    }
-}
-
 impl<T> UndoLogs<T> for TypeVariableUndoLogs
 where
     UndoLog: From<T>,
@@ -193,8 +185,8 @@ fn external_undo_log() {
     let mut undo_log = TypeVariableUndoLogs::default();
 
     let snapshot = undo_log.start_snapshot();
-    storage.with_log(&mut undo_log).new(1);
-    storage.with_log(&mut undo_log).new(2);
+    storage.with_log(&mut undo_log).new_key(1);
+    storage.with_log(&mut undo_log).new_key(2);
     assert_eq!(storage.len(), 2);
 
     undo_log.rollback_to(|| &mut storage, snapshot);