diff --git a/configs/mainnet/phase1.yaml b/configs/mainnet/phase1.yaml
index 8c0800957..78630357f 100644
--- a/configs/mainnet/phase1.yaml
+++ b/configs/mainnet/phase1.yaml
@@ -69,8 +69,6 @@ EARLY_DERIVED_SECRET_PENALTY_MAX_FUTURE_EPOCHS: 32768
 EPOCHS_PER_CUSTODY_PERIOD: 16384
 # 2**11 (= 2,048) epochs, ~9 days
 CUSTODY_PERIOD_TO_RANDAO_PADDING: 2048
-# 2**14 (= 16,384) epochs
-CUSTODY_RESPONSE_DEADLINE: 16384
 # 2**15 (= 32,768) epochs, ~146 days
 MAX_CHUNK_CHALLENGE_DELAY: 32768
 
diff --git a/configs/minimal/phase1.yaml b/configs/minimal/phase1.yaml
index 7fbc7e5a3..b4b738660 100644
--- a/configs/minimal/phase1.yaml
+++ b/configs/minimal/phase1.yaml
@@ -66,15 +66,13 @@ DOMAIN_LIGHT_AGGREGATE_AND_PROOF: 0x85000000
 # 2**1 (= 2) epochs
 RANDAO_PENALTY_EPOCHS: 2
 # [customized] quicker for testing
-EARLY_DERIVED_SECRET_PENALTY_MAX_FUTURE_EPOCHS: 128
+EARLY_DERIVED_SECRET_PENALTY_MAX_FUTURE_EPOCHS: 64
 # [customized] quicker for testing
-EPOCHS_PER_CUSTODY_PERIOD: 64
+EPOCHS_PER_CUSTODY_PERIOD: 32
 # [customized] quicker for testing
 CUSTODY_PERIOD_TO_RANDAO_PADDING: 8
-# [customized] quicker for testing
-CUSTODY_RESPONSE_DEADLINE: 128
 # [customize for faster testing]
-MAX_CHUNK_CHALLENGE_DELAY: 128
+MAX_CHUNK_CHALLENGE_DELAY: 64
 
 
 # Misc parameters
diff --git a/specs/phase1/custody-game.md b/specs/phase1/custody-game.md
index 8d9c89c56..6746c26e2 100644
--- a/specs/phase1/custody-game.md
+++ b/specs/phase1/custody-game.md
@@ -72,7 +72,6 @@ This document details the beacon chain additions and changes in Phase 1 of Ether
 | `EPOCHS_PER_CUSTODY_PERIOD` | `2**14` (= 16,384) | epochs | ~73 days |
 | `CUSTODY_PERIOD_TO_RANDAO_PADDING` | `2**11` (= 2,048) | epochs | ~9 days |
 | `MAX_CHUNK_CHALLENGE_DELAY` | `2**15` (= 32,768) | epochs | ~146 days |
-| `CHUNK_RESPONSE_DEADLINE` | `2**14` (= 16,384) | epochs | ~73 days |
 
 ### Max operations per block
 
diff --git a/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_custody_slashing.py b/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_custody_slashing.py
index 07cd76996..861922884 100644
--- a/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_custody_slashing.py
+++ b/tests/core/pyspec/eth2spec/test/phase1/block_processing/test_process_custody_slashing.py
@@ -124,7 +124,7 @@ def test_multiple_epochs_custody(spec, state):
 @with_all_phases_except([PHASE0])
 @spec_state_test
 def test_many_epochs_custody(spec, state):
-    yield from run_standard_custody_slashing_test(spec, state, shard_lateness=spec.SLOTS_PER_EPOCH * 10)
+    yield from run_standard_custody_slashing_test(spec, state, shard_lateness=spec.SLOTS_PER_EPOCH * 5)
 
 
 @with_all_phases_except([PHASE0])