diff --git a/lib/src/dag_walk.rs b/lib/src/dag_walk.rs
index 782c04030..1c2022eae 100644
--- a/lib/src/dag_walk.rs
+++ b/lib/src/dag_walk.rs
@@ -88,8 +88,8 @@ where
 
 pub fn leaves<T, ID, II, NI>(
     start: II,
-    mut neighbors_fn: impl FnMut(&T) -> NI,
     id_fn: impl Fn(&T) -> ID,
+    mut neighbors_fn: impl FnMut(&T) -> NI,
 ) -> HashSet<T>
 where
     T: Hash + Eq + Clone,
@@ -125,8 +125,8 @@ where
 /// start set.
 pub fn heads<T, ID, II, NI>(
     start: II,
-    neighbors_fn: impl Fn(&T) -> NI,
     id_fn: impl Fn(&T) -> ID,
+    mut neighbors_fn: impl FnMut(&T) -> NI,
 ) -> HashSet<T>
 where
     T: Hash + Eq + Clone,
@@ -149,8 +149,8 @@ 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,
+    mut neighbors_fn: impl FnMut(&T) -> NI,
 ) -> Option<T>
 where
     T: Hash + Eq + Clone,
@@ -309,8 +309,8 @@ mod tests {
         let common = closest_common_node(
             vec!['E'],
             vec!['H'],
-            |node| neighbors[node].clone(),
             |node| *node,
+            |node| neighbors[node].clone(),
         );
 
         // TODO: fix the implementation to return B
@@ -340,16 +340,16 @@ mod tests {
 
         let actual = heads(
             vec!['A', 'C', 'D', 'F'],
-            |node| neighbors[node].clone(),
             |node| *node,
+            |node| neighbors[node].clone(),
         );
         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(),
         );
         assert_eq!(actual, hashset!['D', 'F']);
     }
diff --git a/lib/src/op_heads_store.rs b/lib/src/op_heads_store.rs
index 9a5f486bd..88f5d966e 100644
--- a/lib/src/op_heads_store.rs
+++ b/lib/src/op_heads_store.rs
@@ -52,10 +52,13 @@ pub trait OpHeadsStore: Send + Sync + Debug {
     /// storage.
     fn handle_ancestor_ops(&self, op_heads: Vec<Operation>) -> Vec<Operation> {
         let op_head_ids_before: HashSet<_> = op_heads.iter().map(|op| op.id().clone()).collect();
-        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,
+            |op: &Operation| op.id().clone(),
+            |op: &Operation| op.parents(),
+        );
         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 685362a99..42953ab51 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(),
         )
         .unwrap();
         let repo_loader = self.base_repo().loader();
diff --git a/src/cli_util.rs b/src/cli_util.rs
index 68f0c6532..caf24faf3 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(),
         );
         if let Some(ancestor_op) = maybe_ancestor_op {
             if ancestor_op.id() == repo_operation.id() {