1 files changed, 1 insertions, 1 deletions

diff --git a/lib/arena/src/lib.rs b/lib/arena/src/lib.rs
index bce15c867..1720537cb 100644
--- a/lib/arena/src/lib.rs
+++ b/lib/arena/src/lib.rs
@@ -90,7 +90,7 @@ impl<T> Idx<T> {
 }
 
 /// Yet another index-based arena.
-#[derive(Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq, Hash)]
 pub struct Arena<T> {
     data: Vec<T>,
 }