diff --git a/pycardano/governance.py b/pycardano/governance.py
index c217fc4f..edf2ffaa 100644
--- a/pycardano/governance.py
+++ b/pycardano/governance.py
@@ -416,13 +416,13 @@ class HardForkInitiationAction(CodedSerializable):
     gov_action_id: Optional[GovActionId]
     """Optional reference to a previous governance action"""
 
-    protocol_version: Fraction
+    protocol_version: Tuple[int, int]
     """The target protocol version as (major, minor) version numbers"""
 
     def __post_init__(self):
         major, minor = self.protocol_version
-        if not 1 <= major <= 10:
-            raise ValueError("Major protocol version must be between 1 and 10")
+        if not 0 <= major <= 12:
+            raise ValueError("Major protocol version must be between 0 and 12")
 
 
 class TreasuryWithdrawal(DictCBORSerializable):
diff --git a/pycardano/serialization.py b/pycardano/serialization.py
index 2422b3f3..47310fa8 100644
--- a/pycardano/serialization.py
+++ b/pycardano/serialization.py
@@ -836,6 +836,19 @@ def _restore_typed_primitive(
             raise DeserializeException(f"Expected type list but got {type(v)}")
         v_list = [_restore_typed_primitive(t_subtype, w) for w in v]
         return v.__class__(v_list)
+    elif hasattr(t, "__origin__") and (t.__origin__ is tuple):
+        t_args = t.__args__
+        if not isinstance(v, (list, IndefiniteList)):
+            raise DeserializeException(f"Expected type list but got {type(v)}")
+        if len(t_args) == 2 and t_args[1] is Ellipsis:
+            return tuple(_restore_typed_primitive(t_args[0], w) for w in v)
+        if len(t_args) != len(v):
+            raise DeserializeException(
+                f"Tuple types need exactly {len(v)} type arguments, but got {t_args}"
+            )
+        return tuple(
+            _restore_typed_primitive(t_subtype, w) for t_subtype, w in zip(t_args, v)
+        )
     elif isclass(t) and t == ByteString:
         if not isinstance(v, bytes):
             raise DeserializeException(f"Expected type bytes but got {type(v)}")
diff --git a/test/pycardano/test_governance.py b/test/pycardano/test_governance.py
index 2f9b933f..a4bfa96e 100644
--- a/test/pycardano/test_governance.py
+++ b/test/pycardano/test_governance.py
@@ -373,12 +373,34 @@ def test_invalid_protocol_version(self):
         gov_action_id = GovActionId(transaction_id=tx_id, gov_action_index=1)
 
         with pytest.raises(
-            ValueError, match="Major protocol version must be between 1 and 10"
+            ValueError, match="Major protocol version must be between 0 and 12"
         ):
             HardForkInitiationAction(
-                gov_action_id=gov_action_id, protocol_version=(11, 0)
+                gov_action_id=gov_action_id, protocol_version=(13, 0)
             )
 
+    def test_hard_fork_action_cbor_round_trip(self):
+        # The ledger encodes protocol_version as a [major, minor] array
+        # (Conway CDDL: protocol_version = [major_protocol_version,
+        # uint .size 4], major in 0..12). Protocol version 11 is the
+        # version live on mainnet, so it must be constructible.
+        action = HardForkInitiationAction(
+            gov_action_id=None, protocol_version=(11, 0)
+        )
+
+        assert action.to_cbor_hex() == "8301f6820b00"
+        assert HardForkInitiationAction.from_cbor(action.to_cbor()) == action
+
+    def test_hard_fork_action_cbor_round_trip_with_gov_action_id(self):
+        tx_id = TransactionId(bytes.fromhex("ff" * TRANSACTION_HASH_SIZE))
+        gov_action_id = GovActionId(transaction_id=tx_id, gov_action_index=65535)
+
+        action = HardForkInitiationAction(
+            gov_action_id=gov_action_id, protocol_version=(10, 0)
+        )
+
+        assert HardForkInitiationAction.from_cbor(action.to_cbor()) == action
+
 
 class TestUpdateCommittee:
     def test_update_committee_creation(self):