diff --git a/safe_transaction_service/history/serializers.py b/safe_transaction_service/history/serializers.py
index f724292ce..fdb071918 100644
--- a/safe_transaction_service/history/serializers.py
+++ b/safe_transaction_service/history/serializers.py
@@ -570,12 +570,13 @@ def validate(self, attrs):
             ):
                 raise ValidationError("Only EOA and ETH_SIGN signatures are supported")
 
+            owner = safe_signature.owner
             # The transaction can be deleted by the proposer or by the delegate user who proposed it.
-            if safe_signature.owner == proposer:
+            if owner == proposer:
                 return attrs
             if (
                 multisig_tx.proposed_by_delegate
-                and safe_signature.owner == multisig_tx.proposed_by_delegate
+                and owner == multisig_tx.proposed_by_delegate
             ):
                 delegates_for_proposer = (
                     SafeContractDelegate.objects.get_delegates_for_safe_and_owners(
@@ -583,7 +584,7 @@ def validate(self, attrs):
                     )
                 )
                 # Check if it's still a valid delegate.
-                if safe_signature.owner in delegates_for_proposer:
+                if owner in delegates_for_proposer:
                     return attrs
 
         raise ValidationError(