diff --git a/linera-chain/src/inbox.rs b/linera-chain/src/inbox.rs
index c0a496018ed..f8cb6f8ee9f 100644
--- a/linera-chain/src/inbox.rs
+++ b/linera-chain/src/inbox.rs
@@ -39,7 +39,7 @@ static INBOX_SIZE: LazyLock<HistogramVec> = LazyLock::new(|| {
         "inbox_size",
         "Inbox size",
         &[],
-        exponential_bucket_interval(1.0, 500_000.0),
+        exponential_bucket_interval(1.0, 2_000_000.0),
     )
 });