diff --git a/lib/src/default_index_store.rs b/lib/src/default_index_store.rs
index ad4e98773..62b49d8f8 100644
--- a/lib/src/default_index_store.rs
+++ b/lib/src/default_index_store.rs
@@ -493,6 +493,10 @@ impl MutableIndexImpl {
         }
     }
 
+    pub fn as_composite(&self) -> CompositeIndex {
+        CompositeIndex(self)
+    }
+
     pub(crate) fn add_commit_data(
         &mut self,
         commit_id: CommitId,
@@ -509,7 +513,7 @@ impl MutableIndexImpl {
             parent_positions: vec![],
         };
         for parent_id in parent_ids {
-            let parent_entry = self
+            let parent_entry = CompositeIndex(self)
                 .entry_by_id(parent_id)
                 .expect("parent commit is not indexed");
             entry.generation_number = max(
@@ -699,10 +703,6 @@ impl Index for MutableIndexImpl {
         CompositeIndex(self).resolve_prefix(prefix)
     }
 
-    fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry> {
-        CompositeIndex(self).entry_by_id(commit_id)
-    }
-
     fn has_id(&self, commit_id: &CommitId) -> bool {
         CompositeIndex(self).has_id(commit_id)
     }
@@ -953,7 +953,7 @@ impl<'a> CompositeIndex<'a> {
             })
     }
 
-    pub(crate) fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry<'a>> {
+    pub fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry<'a>> {
         self.commit_id_to_pos(commit_id)
             .map(|pos| self.entry_by_pos(pos))
     }
@@ -1781,10 +1781,6 @@ impl Index for ReadonlyIndexImpl {
         CompositeIndex(self).resolve_prefix(prefix)
     }
 
-    fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry> {
-        CompositeIndex(self).entry_by_id(commit_id)
-    }
-
     fn has_id(&self, commit_id: &CommitId) -> bool {
         CompositeIndex(self).has_id(commit_id)
     }
diff --git a/lib/src/default_revset_engine.rs b/lib/src/default_revset_engine.rs
index f658a73f4..439304ce9 100644
--- a/lib/src/default_revset_engine.rs
+++ b/lib/src/default_revset_engine.rs
@@ -944,7 +944,6 @@ mod tests {
     use super::*;
     use crate::backend::{ChangeId, CommitId, ObjectId};
     use crate::default_index_store::MutableIndexImpl;
-    use crate::index::Index;
 
     #[test]
     fn test_id_index_resolve_prefix() {
@@ -1073,7 +1072,7 @@ mod tests {
         index.add_commit_data(id_3.clone(), new_change_id(), &[id_2.clone()]);
         index.add_commit_data(id_4.clone(), new_change_id(), &[id_3.clone()]);
 
-        let get_entry = |id: &CommitId| index.entry_by_id(id).unwrap();
+        let get_entry = |id: &CommitId| index.as_composite().entry_by_id(id).unwrap();
         let make_entries = |ids: &[&CommitId]| ids.iter().map(|id| get_entry(id)).collect_vec();
         let make_set = |ids: &[&CommitId]| -> Box<dyn InternalRevset> {
             let index_entries = make_entries(ids);
diff --git a/lib/src/index.rs b/lib/src/index.rs
index 16209835d..5af6a6ce4 100644
--- a/lib/src/index.rs
+++ b/lib/src/index.rs
@@ -20,7 +20,7 @@ use thiserror::Error;
 
 use crate::backend::{CommitId, ObjectId};
 use crate::commit::Commit;
-use crate::default_index_store::{IndexEntry, RevWalk};
+use crate::default_index_store::RevWalk;
 use crate::op_store::OperationId;
 use crate::operation::Operation;
 use crate::revset::{ResolvedExpression, Revset, RevsetEvaluationError};
@@ -53,8 +53,6 @@ pub trait Index: Send + Sync {
 
     fn resolve_prefix(&self, prefix: &HexPrefix) -> PrefixResolution<CommitId>;
 
-    fn entry_by_id(&self, commit_id: &CommitId) -> Option<IndexEntry>;
-
     fn has_id(&self, commit_id: &CommitId) -> bool;
 
     fn is_ancestor(&self, ancestor_id: &CommitId, descendant_id: &CommitId) -> bool;
diff --git a/lib/tests/test_index.rs b/lib/tests/test_index.rs
index 69c2f253a..f34a70a96 100644
--- a/lib/tests/test_index.rs
+++ b/lib/tests/test_index.rs
@@ -36,7 +36,11 @@ fn child_commit<'repo>(
 
 // Helper just to reduce line wrapping
 fn generation_number(index: &ReadonlyIndexImpl, commit_id: &CommitId) -> u32 {
-    index.entry_by_id(commit_id).unwrap().generation_number()
+    index
+        .as_composite()
+        .entry_by_id(commit_id)
+        .unwrap()
+        .generation_number()
 }
 
 #[test_case(false ; "local backend")]