diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 8a90bc2f4..71566baab 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -198,7 +198,7 @@ The following values are (non-configurable) constants used throughout the specif
 | - | - |
 | `GENESIS_SLOT` | `Slot(0)` |
 | `GENESIS_EPOCH` | `Epoch(0)` |
-| `BLS_WITHDRAWAL_PREFIX` | `Bytes1()` |
+| `BLS_WITHDRAWAL_PREFIX` | `Bytes1(b'\x00')` |
 
 ### Time parameters