diff --git a/lib/src/operation.rs b/lib/src/operation.rs
index 510db0b977..d88446cb0b 100644
--- a/lib/src/operation.rs
+++ b/lib/src/operation.rs
@@ -76,7 +76,7 @@ impl Operation {
         &self.id
     }
 
-    pub fn parent_ids(&self) -> &Vec<OperationId> {
+    pub fn parent_ids(&self) -> &[OperationId] {
         &self.data.parents
     }