diff --git a/src/packet.rs b/src/packet.rs
index ddd24c9de1..5ca3055bc7 100644
--- a/src/packet.rs
+++ b/src/packet.rs
@@ -340,7 +340,7 @@ pub fn to_blobs<T: Serialize>(
 }
 
 const BLOB_INDEX_END: usize = size_of::<u64>();
-const BLOB_ID_END: usize = BLOB_INDEX_END + size_of::<usize>() + size_of::<Pubkey>();
+const BLOB_ID_END: usize = BLOB_INDEX_END + size_of::<Pubkey>();
 const BLOB_FLAGS_END: usize = BLOB_ID_END + size_of::<u32>();
 const BLOB_SIZE_END: usize = BLOB_FLAGS_END + size_of::<u64>();
 
diff --git a/src/transaction.rs b/src/transaction.rs
index b894d7ed29..09be5027f7 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -6,10 +6,11 @@ use chrono::prelude::*;
 use hash::Hash;
 use payment_plan::{Payment, PaymentPlan, Witness};
 use signature::{Keypair, KeypairUtil, Pubkey, Signature};
+use std::mem::size_of;
 
-pub const SIGNED_DATA_OFFSET: usize = 96;
+pub const SIGNED_DATA_OFFSET: usize = PUB_KEY_OFFSET + size_of::<Pubkey>();
 pub const SIG_OFFSET: usize = 0;
-pub const PUB_KEY_OFFSET: usize = 64;
+pub const PUB_KEY_OFFSET: usize = size_of::<Signature>();
 
 /// The type of payment plan. Each item must implement the PaymentPlan trait.
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]