diff --git a/cashu/core/base.py b/cashu/core/base.py
index 45f3c31..ede0d8f 100644
--- a/cashu/core/base.py
+++ b/cashu/core/base.py
@@ -99,6 +99,9 @@ class Proof(BaseModel):
     def from_dict(cls, proof_dict: dict):
         if proof_dict.get("dleq") and isinstance(proof_dict["dleq"], str):
             proof_dict["dleq"] = DLEQWallet(**json.loads(proof_dict["dleq"]))
+        else:
+            # overwrite the empty string with None
+            proof_dict["dleq"] = None
         c = cls(**proof_dict)
         return c