diff --git a/lib/src/rewrite.rs b/lib/src/rewrite.rs
index df0163fe7..d8c16657c 100644
--- a/lib/src/rewrite.rs
+++ b/lib/src/rewrite.rs
@@ -108,7 +108,7 @@ pub fn back_out_commit(
 ) -> Result<Commit, TreeMergeError> {
     let old_base_tree = merge_commit_trees(mut_repo, &old_commit.parents())?;
     let new_base_tree = merge_commit_trees(mut_repo, new_parents)?;
-    let new_tree = merge_trees(&new_base_tree, &old_commit.tree(), &old_base_tree).unwrap();
+    let new_tree = merge_trees(&new_base_tree, &old_commit.tree(), &old_base_tree)?;
     let new_parent_ids = new_parents
         .iter()
         .map(|commit| commit.id().clone())