diff --git a/configs/mainnet/altair.yaml b/configs/mainnet/altair.yaml
index 3cd4b8419..6db260cca 100644
--- a/configs/mainnet/altair.yaml
+++ b/configs/mainnet/altair.yaml
@@ -47,8 +47,6 @@ ALTAIR_FORK_EPOCH: 18446744073709551615
 MIN_SYNC_COMMITTEE_PARTICIPANTS: 1
 # 2**13
 MAX_VALID_LIGHT_CLIENT_UPDATES: 8192
-# 2**13 (=8192)
-LIGHT_CLIENT_UPDATE_TIMEOUT: 8192
 
 
 # Validator
diff --git a/configs/minimal/altair.yaml b/configs/minimal/altair.yaml
index f9b30eea2..5c5781010 100644
--- a/configs/minimal/altair.yaml
+++ b/configs/minimal/altair.yaml
@@ -47,8 +47,6 @@ ALTAIR_FORK_EPOCH: 18446744073709551615
 MIN_SYNC_COMMITTEE_PARTICIPANTS: 1
 # [customized]
 MAX_VALID_LIGHT_CLIENT_UPDATES: 32
-# [customized]
-LIGHT_CLIENT_UPDATE_TIMEOUT: 32
 
 # Validator
 # ---------------------------------------------------------------
diff --git a/specs/altair/sync-protocol.md b/specs/altair/sync-protocol.md
index fba263bb1..ca55c92f7 100644
--- a/specs/altair/sync-protocol.md
+++ b/specs/altair/sync-protocol.md
@@ -12,7 +12,6 @@
 - [Constants](#constants)
 - [Configuration](#configuration)
   - [Misc](#misc)
-  - [Time parameters](#time-parameters)
 - [Containers](#containers)
   - [`LightClientSnapshot`](#lightclientsnapshot)
   - [`LightClientUpdate`](#lightclientupdate)
@@ -53,12 +52,6 @@ uses sync committees introduced in [this beacon chain extension](./beacon-chain.
 | `MIN_SYNC_COMMITTEE_PARTICIPANTS` | `1` |
 | `MAX_VALID_LIGHT_CLIENT_UPDATES` | `uint64(2**64 - 1)` |
 
-### Time parameters
-
-| Name | Value | Unit | Duration |
-| - | - | :-: | :-: |
-| `LIGHT_CLIENT_UPDATE_TIMEOUT` | `Slot(2**13)` | slots | ~27 hours |
-
 ## Containers
 
 ### `LightClientSnapshot`
@@ -184,6 +177,7 @@ def process_light_client_update(store: LightClientStore, update: LightClientUpda
     validate_light_client_update(store.snapshot, update, genesis_validators_root)
     store.valid_updates.append(update)
 
+    update_timeout = SLOTS_PER_EPOCH * EPOCHS_PER_SYNC_COMMITTEE_PERIOD
     if (
         sum(update.sync_committee_bits) * 3 >= len(update.sync_committee_bits) * 2
         and update.finality_header != BeaconBlockHeader()
@@ -193,7 +187,7 @@ def process_light_client_update(store: LightClientStore, update: LightClientUpda
         # It may be changed to re-organizable light client design. See the on-going issue eth2.0-specs#2182.
         apply_light_client_update(store.snapshot, update)
         store.valid_updates = []
-    elif current_slot > store.snapshot.header.slot + LIGHT_CLIENT_UPDATE_TIMEOUT:
+    elif current_slot > store.snapshot.header.slot + update_timeout:
         # Forced best update when the update timeout has elapsed
         apply_light_client_update(store.snapshot,
                                   max(store.valid_updates, key=lambda update: sum(update.sync_committee_bits)))