diff --git a/safe_transaction_service/history/serializers.py b/safe_transaction_service/history/serializers.py
index c8306364b..0be6822ae 100644
--- a/safe_transaction_service/history/serializers.py
+++ b/safe_transaction_service/history/serializers.py
@@ -359,7 +359,7 @@ def check_delegate_signature(
 
 
 class DelegateSerializer(DelegateSignatureCheckerMixin, serializers.Serializer):
-    safe = EthereumAddressField(allow_null=True)
+    safe = EthereumAddressField(allow_null=True, required=False)
     delegate = EthereumAddressField()
     delegator = EthereumAddressField()
     signature = HexadecimalField(min_length=65)
@@ -377,7 +377,7 @@ def get_safe_owners(
     def validate(self, data):
         super().validate(data)
 
-        safe_address: Optional[ChecksumAddress] = data["safe"]
+        safe_address: Optional[ChecksumAddress] = data.get("safe")
         if (
             safe_address
             and not SafeContract.objects.filter(address=safe_address).exists()
diff --git a/safe_transaction_service/history/tests/test_views.py b/safe_transaction_service/history/tests/test_views.py
index b99b29320..3e931d2cb 100644
--- a/safe_transaction_service/history/tests/test_views.py
+++ b/safe_transaction_service/history/tests/test_views.py
@@ -1607,7 +1607,6 @@ def test_delegates_post(self):
         delegator = Account.create()
         label = "Saul Goodman"
         data = {
-            "safe": None,
             "delegate": delegate.address,
             "delegator": delegator.address,
             "label": label,
diff --git a/safe_transaction_service/history/views.py b/safe_transaction_service/history/views.py
index 337caebda..8e39686a9 100644
--- a/safe_transaction_service/history/views.py
+++ b/safe_transaction_service/history/views.py
@@ -593,7 +593,7 @@ def post(self, request, address, **kwargs):
         signer will update the label or delegator if different.
         For the signature we are using TOTP with `T0=0` and `Tx=3600`. TOTP is calculated by taking the
         Unix UTC epoch time (no milliseconds) and dividing by 3600 (natural division, no decimals)
-        For signature this hash need to be signed: keccak(address + str(int(current_epoch // 3600)))
+        For signature this hash need to be signed: keccak(checksummed address + str(int(current_epoch // 3600)))
         For example:
              - We want to add the delegate `0x132512f995866CcE1b0092384A6118EDaF4508Ff` and `epoch=1586779140`.
              - `TOTP = epoch // 3600 = 1586779140 // 3600 = 440771`
@@ -715,7 +715,7 @@ def post(self, request, **kwargs):
         signer will update the label or delegator if different.
         For the signature we are using TOTP with `T0=0` and `Tx=3600`. TOTP is calculated by taking the
         Unix UTC epoch time (no milliseconds) and dividing by 3600 (natural division, no decimals)
-        For signature this hash need to be signed: keccak(address + str(int(current_epoch // 3600)))
+        For signature this hash need to be signed: keccak(checksummed address + str(int(current_epoch // 3600)))
         For example:
              - We want to add the delegate `0x132512f995866CcE1b0092384A6118EDaF4508Ff` and `epoch=1586779140`.
              - `TOTP = epoch // 3600 = 1586779140 // 3600 = 440771`