diff --git a/specs/phase1/beacon-chain.md b/specs/phase1/beacon-chain.md
index 4e4778abe..a84d432a1 100644
--- a/specs/phase1/beacon-chain.md
+++ b/specs/phase1/beacon-chain.md
@@ -252,8 +252,8 @@ class BeaconBlockBody(Container):
     deposits: List[Deposit, MAX_DEPOSITS]
     voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS]
     # Custody game
-    chunk_challenges: List[CustodyChunkResponse, MAX_CUSTODY_CHUNK_CHALLENGES]
-    chunk_challenge_responses: List[CustodyChunkResponse, MAX_CUSTODY_CHUNK_CHALLENGE_RESPONSES]
+    chunk_challenges: List[CustodyChunkChallenge, MAX_CUSTODY_CHUNK_CHALLENGES]
+    chunk_challenge_responses: List[CustodyChunkChallenge, MAX_CUSTODY_CHUNK_CHALLENGE_RESPONSES]
     custody_key_reveals: List[CustodyKeyReveal, MAX_CUSTODY_KEY_REVEALS]
     early_derived_secret_reveals: List[EarlyDerivedSecretReveal, MAX_EARLY_DERIVED_SECRET_REVEALS]
     custody_slashings: List[SignedCustodySlashing, MAX_CUSTODY_SLASHINGS]