diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Allegra b/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Allegra
index ff1454cb65..cdf13156ce 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Alonzo b/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Alonzo
index c125d5e64c..fbe811b259 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Mary b/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Mary
index bc28882863..2ca5cf75bb 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Shelley b/ouroboros-consensus-cardano/golden/cardano/disk/ChainDepState_Shelley
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Allegra b/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Allegra
index 4ad881b9b3..e5219707cd 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Alonzo b/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Alonzo
index 666a38e853..57bfc0c5b8 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Mary b/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Mary
index e203d27144..686aa6d513 100644
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diff --git a/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Shelley b/ouroboros-consensus-cardano/golden/cardano/disk/ExtLedgerState_Shelley
index ea839ed0df..a2f8d55327 100644
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diff --git a/ouroboros-consensus-cardano/golden/shelley/disk/ChainDepState b/ouroboros-consensus-cardano/golden/shelley/disk/ChainDepState
index 6f89eb5346..12ed7861d5 100644
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diff --git a/ouroboros-consensus-cardano/golden/shelley/disk/ExtLedgerState b/ouroboros-consensus-cardano/golden/shelley/disk/ExtLedgerState
index fa42962234..b9e175b8b7 100644
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diff --git a/ouroboros-consensus-protocol/changelog.d/20250528_162423_javier.sagredo_withoriginth.md b/ouroboros-consensus-protocol/changelog.d/20250528_162423_javier.sagredo_withoriginth.md
new file mode 100644
index 0000000000..5207ac84d2
--- /dev/null
+++ b/ouroboros-consensus-protocol/changelog.d/20250528_162423_javier.sagredo_withoriginth.md
@@ -0,0 +1,22 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+-->
+
+<!--
+### Patch
+
+- A bullet item for the Patch category.
+
+-->
+<!--
+### Non-Breaking
+
+- A bullet item for the Non-Breaking category.
+
+-->
+
+### Breaking
+
+- Encode the slot number in the TPraos state as `[] / [slot]` instead of `[0] / [1, slot]`.
diff --git a/ouroboros-consensus-protocol/src/ouroboros-consensus-protocol/Ouroboros/Consensus/Protocol/TPraos.hs b/ouroboros-consensus-protocol/src/ouroboros-consensus-protocol/Ouroboros/Consensus/Protocol/TPraos.hs
index 6f622d2157..7d6288ff3d 100644
--- a/ouroboros-consensus-protocol/src/ouroboros-consensus-protocol/Ouroboros/Consensus/Protocol/TPraos.hs
+++ b/ouroboros-consensus-protocol/src/ouroboros-consensus-protocol/Ouroboros/Consensus/Protocol/TPraos.hs
@@ -83,6 +83,7 @@ import qualified Ouroboros.Consensus.Protocol.Ledger.HotKey as HotKey
 import Ouroboros.Consensus.Protocol.Ledger.Util
 import Ouroboros.Consensus.Protocol.Praos.Common
 import Ouroboros.Consensus.Ticked
+import Ouroboros.Consensus.Util.CBOR
 import Ouroboros.Consensus.Util.Condense
 import Ouroboros.Consensus.Util.Versioned
 
@@ -283,7 +284,7 @@ instance Serialise TPraosState where
     encodeVersion serialisationFormatVersion1 $
       mconcat
         [ CBOR.encodeListLen 2
-        , toCBOR slot
+        , encodeWithOrigin toCBOR slot
         , toCBOR chainDepState
         ]
 
@@ -293,7 +294,7 @@ instance Serialise TPraosState where
    where
     decodeTPraosState1 = do
       enforceSize "TPraosState" 2
-      TPraosState <$> fromCBOR <*> fromCBOR
+      TPraosState <$> decodeWithOrigin fromCBOR <*> fromCBOR
 
 data instance Ticked TPraosState = TickedChainDepState
   { tickedTPraosStateChainDepState :: SL.ChainDepState