diff --git a/crates/ra_arena/src/lib.rs b/crates/ra_arena/src/lib.rs
index 69b5f10e08..26641e6903 100644
--- a/crates/ra_arena/src/lib.rs
+++ b/crates/ra_arena/src/lib.rs
@@ -71,6 +71,9 @@ impl<ID: ArenaId, T> Arena<ID, T> {
     pub fn len(&self) -> usize {
         self.data.len()
     }
+    pub fn is_empty(&self) -> bool {
+        self.data.is_empty()
+    }
     pub fn alloc(&mut self, value: T) -> ID {
         let id = RawId(self.data.len() as u32);
         self.data.push(value);