diff --git a/eras/byron/ledger/impl/CHANGELOG.md b/eras/byron/ledger/impl/CHANGELOG.md
index 9e7c30cb635..2b16a34fd7d 100644
--- a/eras/byron/ledger/impl/CHANGELOG.md
+++ b/eras/byron/ledger/impl/CHANGELOG.md
@@ -1,8 +1,8 @@
 # Revision history for `cardano-ledger-byron`
 
-## 1.0.1.1
+## 1.0.2.0
 
-*
+* `force` `startTime` in the evaluation of genesis-data. #4574
 
 ## 1.0.1.0
 
diff --git a/eras/byron/ledger/impl/cardano-ledger-byron.cabal b/eras/byron/ledger/impl/cardano-ledger-byron.cabal
index 7b8abbe8d76..f3b09d2ac41 100644
--- a/eras/byron/ledger/impl/cardano-ledger-byron.cabal
+++ b/eras/byron/ledger/impl/cardano-ledger-byron.cabal
@@ -1,6 +1,6 @@
 cabal-version:      3.0
 name:               cardano-ledger-byron
-version:            1.0.1.0
+version:            1.0.2.0
 license:            Apache-2.0
 maintainer:         operations@iohk.io
 author:             IOHK
@@ -243,7 +243,6 @@ library
         contra-tracer,
         cryptonite,
         Cabal-syntax,
-        deepseq,
         digest,
         directory,
         filepath,
diff --git a/eras/byron/ledger/impl/src/Cardano/Chain/Genesis/Data.hs b/eras/byron/ledger/impl/src/Cardano/Chain/Genesis/Data.hs
index 8b960e01c23..2dc8d24dc06 100644
--- a/eras/byron/ledger/impl/src/Cardano/Chain/Genesis/Data.hs
+++ b/eras/byron/ledger/impl/src/Cardano/Chain/Genesis/Data.hs
@@ -29,7 +29,6 @@ import Cardano.Crypto (
  )
 import Cardano.Ledger.Binary
 import Cardano.Prelude
-import Control.DeepSeq ((<$!!>))
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Lazy as BSL
 import Data.List (lookup)
@@ -49,7 +48,6 @@ import Text.JSON.Canonical (
   parseCanonicalJSON,
   renderCanonicalJSON,
  )
-import Prelude (id)
 
 -- | Genesis data contains all data which determines consensus rules. It must be
 --   same for all nodes. It's used to initialize global state, slotting, etc.
@@ -95,7 +93,7 @@ instance MonadError SchemaError m => FromJSON m GenesisData where
     GenesisData
       <$> fromJSField obj "bootStakeholders"
       <*> fromJSField obj "heavyDelegation"
-      <*> (id <$!!> fromJSField obj "startTime")
+      <*> (force <$> fromJSField obj "startTime")
       <*> fromJSField obj "nonAvvmBalances"
       <*> fromJSField obj "blockVersionData"
       -- The above is called blockVersionData for backwards compatibility with