diff --git a/scripts/build_spec.py b/scripts/build_spec.py
index 67c9a547c..1a719cb29 100644
--- a/scripts/build_spec.py
+++ b/scripts/build_spec.py
@@ -163,8 +163,6 @@ def objects_to_spec(functions: Dict[str, str],
             del functions[k]
     functions_spec = '\n\n'.join(functions.values())
     for k in list(constants.keys()):
-        if k.startswith('DOMAIN_'):
-            constants[k] = f"DomainType(({constants[k]}).to_bytes(length=4, byteorder='little'))"
         if k == "BLS12_381_Q":
             constants[k] += "  # noqa: E501"
     constants_spec = '\n'.join(map(lambda x: '%s = %s' % (x, constants[x]), constants))
diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 9c0b9fe66..647d1c9bd 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -199,7 +199,7 @@ The following values are (non-configurable) constants used throughout the specif
 | - | - |
 | `GENESIS_SLOT` | `Slot(0)` |
 | `GENESIS_EPOCH` | `Epoch(0)` |
-| `BLS_WITHDRAWAL_PREFIX` | `Bytes1(b'\x00')` |
+| `BLS_WITHDRAWAL_PREFIX` | `Bytes1('0x00')` |
 
 ### Time parameters
 
@@ -249,15 +249,13 @@ The following values are (non-configurable) constants used throughout the specif
 
 ### Domain types
 
-The following types are defined, mapping into `DomainType` (little endian):
-
 | Name | Value |
 | - | - |
-| `DOMAIN_BEACON_PROPOSER` | `0` |
-| `DOMAIN_BEACON_ATTESTER` | `1` |
-| `DOMAIN_RANDAO` | `2` |
-| `DOMAIN_DEPOSIT` | `3` |
-| `DOMAIN_VOLUNTARY_EXIT` | `4` |
+| `DOMAIN_BEACON_PROPOSER` | `DomainType('0x00000000')` |
+| `DOMAIN_BEACON_ATTESTER` | `DomainType('0x01000000')` |
+| `DOMAIN_RANDAO` | `DomainType('0x02000000')` |
+| `DOMAIN_DEPOSIT` | `DomainType('0x03000000')` |
+| `DOMAIN_VOLUNTARY_EXIT` | `DomainType('0x04000000')` |
 
 ## Containers
 
diff --git a/specs/core/1_custody-game.md b/specs/core/1_custody-game.md
index 017e2a22a..b1f61de2f 100644
--- a/specs/core/1_custody-game.md
+++ b/specs/core/1_custody-game.md
@@ -131,7 +131,7 @@ The following types are defined, mapping into `DomainType` (little endian):
 
 | Name | Value |
 | - | - |
-| `DOMAIN_CUSTODY_BIT_CHALLENGE` | `6` |
+| `DOMAIN_CUSTODY_BIT_CHALLENGE` | `DomainType('0x06000000')` |
 
 ### TODO PLACEHOLDER
 
diff --git a/specs/core/1_shard-data-chains.md b/specs/core/1_shard-data-chains.md
index d5964fe7d..93570dbee 100644
--- a/specs/core/1_shard-data-chains.md
+++ b/specs/core/1_shard-data-chains.md
@@ -101,8 +101,8 @@ This document describes the shard transition function (data layer only) and the
 
 | Name | Value |
 | - | - |
-| `DOMAIN_SHARD_PROPOSER` | `128` |
-| `DOMAIN_SHARD_ATTESTER` | `129` |
+| `DOMAIN_SHARD_PROPOSER` | `DomainType('0x80000000')` |
+| `DOMAIN_SHARD_ATTESTER` | `DomainType('0x81000000')` |
 
 ## Containers
 
diff --git a/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py b/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
index 4bda43360..4ddff1b5e 100644
--- a/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
+++ b/test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py
@@ -451,10 +451,15 @@ class BaseBytes(bytes, Elements, metaclass=BytesType):
     @classmethod
     def extract_args(cls, *args):
         x = args
-        if len(x) == 1 and isinstance(x[0], (GeneratorType, bytes)):
+        if len(x) == 1 and isinstance(x[0], (GeneratorType, bytes, str)):
             x = x[0]
         if isinstance(x, bytes):  # Includes BytesLike
             return x
+        if isinstance(x, str):
+            if x[:2] == '0x':
+                return bytes.fromhex(x[2:])
+            else:
+                return bytes.fromhex(x)
         else:
             return bytes(x)  # E.g. GeneratorType put into bytes.