diff --git a/lib/src/dag_walk.rs b/lib/src/dag_walk.rs
index e333832e0..582608b7f 100644
--- a/lib/src/dag_walk.rs
+++ b/lib/src/dag_walk.rs
@@ -110,8 +110,8 @@ where
 
 pub fn leaves<T, ID, II, NI>(
     start: II,
-    neighbors_fn: &mut impl FnMut(&T) -> NI,
-    id_fn: &impl Fn(&T) -> ID,
+    mut neighbors_fn: impl FnMut(&T) -> NI,
+    id_fn: impl Fn(&T) -> ID,
 ) -> HashSet<T>
 where
     T: Hash + Eq + Clone,
@@ -147,8 +147,8 @@ where
 /// start set.
 pub fn heads<T, ID, II, NI>(
     start: II,
-    neighbors_fn: &impl Fn(&T) -> NI,
-    id_fn: &impl Fn(&T) -> ID,
+    neighbors_fn: impl Fn(&T) -> NI,
+    id_fn: impl Fn(&T) -> ID,
 ) -> HashSet<T>
 where
     T: Hash + Eq + Clone,
@@ -175,8 +175,8 @@ where
 pub fn closest_common_node<T, ID, II1, II2, NI>(
     set1: II1,
     set2: II2,
-    neighbors_fn: &impl Fn(&T) -> NI,
-    id_fn: &impl Fn(&T) -> ID,
+    neighbors_fn: impl Fn(&T) -> NI,
+    id_fn: impl Fn(&T) -> ID,
 ) -> Option<T>
 where
     T: Hash + Eq + Clone,
@@ -341,8 +341,8 @@ mod tests {
         let common = closest_common_node(
             vec!['E'],
             vec!['H'],
-            &|node| neighbors[node].clone(),
-            &|node| *node,
+            |node| neighbors[node].clone(),
+            |node| *node,
         );
 
         // TODO: fix the implementation to return B
@@ -372,16 +372,16 @@ mod tests {
 
         let actual = heads(
             vec!['A', 'C', 'D', 'F'],
-            &|node| neighbors[node].clone(),
-            &|node| *node,
+            |node| neighbors[node].clone(),
+            |node| *node,
         );
         assert_eq!(actual, hashset!['D', 'F']);
 
         // Check with a different order in the start set
         let actual = heads(
             vec!['F', 'D', 'C', 'A'],
-            &|node| neighbors[node].clone(),
-            &|node| *node,
+            |node| neighbors[node].clone(),
+            |node| *node,
         );
         assert_eq!(actual, hashset!['D', 'F']);
     }
diff --git a/lib/src/op_heads_store.rs b/lib/src/op_heads_store.rs
index 7a88a8498..9a5f486bd 100644
--- a/lib/src/op_heads_store.rs
+++ b/lib/src/op_heads_store.rs
@@ -55,7 +55,7 @@ pub trait OpHeadsStore: Send + Sync + Debug {
         let neighbors_fn = |op: &Operation| op.parents();
         // Remove ancestors so we don't create merge operation with an operation and its
         // ancestor
-        let op_heads = dag_walk::heads(op_heads, &neighbors_fn, &|op: &Operation| op.id().clone());
+        let op_heads = dag_walk::heads(op_heads, neighbors_fn, |op: &Operation| op.id().clone());
         let op_head_ids_after: HashSet<_> = op_heads.iter().map(|op| op.id().clone()).collect();
         for removed_op_head in op_head_ids_before.difference(&op_head_ids_after) {
             self.remove_op_head(removed_op_head);
diff --git a/lib/src/transaction.rs b/lib/src/transaction.rs
index d14b80257..685362a99 100644
--- a/lib/src/transaction.rs
+++ b/lib/src/transaction.rs
@@ -68,8 +68,8 @@ impl Transaction {
         let ancestor_op = closest_common_node(
             self.parent_ops.clone(),
             vec![other_op.clone()],
-            &|op: &Operation| op.parents(),
-            &|op: &Operation| op.id().clone(),
+            |op: &Operation| op.parents(),
+            |op: &Operation| op.id().clone(),
         )
         .unwrap();
         let repo_loader = self.base_repo().loader();
diff --git a/src/cli_util.rs b/src/cli_util.rs
index 461216330..68f0c6532 100644
--- a/src/cli_util.rs
+++ b/src/cli_util.rs
@@ -1457,8 +1457,8 @@ pub fn check_stale_working_copy(
         let maybe_ancestor_op = dag_walk::closest_common_node(
             [wc_operation.clone()],
             [repo_operation.clone()],
-            &|op: &Operation| op.parents(),
-            &|op: &Operation| op.id().clone(),
+            |op: &Operation| op.parents(),
+            |op: &Operation| op.id().clone(),
         );
         if let Some(ancestor_op) = maybe_ancestor_op {
             if ancestor_op.id() == repo_operation.id() {