diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 198c4872a..d8d0290b3 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -34,7 +34,6 @@
                 - [`Deposit`](#deposit)
                 - [`DepositData`](#depositdata)
                 - [`DepositInput`](#depositinput)
-                - [`ProofOfPossessionData`](#proofofpossessiondata)
             - [Exits](#exits)
                 - [`Exit`](#exit)
         - [Beacon chain blocks](#beacon-chain-blocks)