diff --git a/common/src/net/post2.rs b/common/src/net/post2.rs
index d864b66055..55cf64c3ee 100644
--- a/common/src/net/post2.rs
+++ b/common/src/net/post2.rs
@@ -267,9 +267,9 @@ impl<S: PostMsg, R: PostMsg> PostBox<S, R> {
                 for _ in 0..100 {
                     match incoming_buf.get(0..9) {
                         Some(len_bytes) => {
-                            let len = usize::from_le_bytes(
+                            let len = u64::from_le_bytes(
                                 <[u8; 8]>::try_from(&len_bytes[0..8]).unwrap(),
-                            ); // Can't fail
+                            ) as usize; // Can't fail
 
                             if len > MAX_MSG_SIZE {
                                 recv_tx.send(Err(Error::InvalidMessage)).unwrap();