diff --git a/cashu/core/base.py b/cashu/core/base.py
index 067c91ae..ad944130 100644
--- a/cashu/core/base.py
+++ b/cashu/core/base.py
@@ -156,7 +156,12 @@ class BlindedMessage(BaseModel):
 
     amount: int
     B_: str  # Hex-encoded blinded message
-    p2pksigs: Union[List[str], None] = None  # signature for p2pk with SIG_ALL
+    witness: Union[str, None] = None  # witnesses (used for P2PK with SIG_ALL)
+
+    @property
+    def p2pksigs(self) -> List[str]:
+        assert self.witness, "Witness is missing"
+        return P2PKWitness.from_witness(self.witness).signatures
 
 
 class BlindedSignature(BaseModel):
diff --git a/cashu/wallet/p2pk.py b/cashu/wallet/p2pk.py
index 16ac2f01..21d7e593 100644
--- a/cashu/wallet/p2pk.py
+++ b/cashu/wallet/p2pk.py
@@ -155,7 +155,7 @@ async def add_p2pk_witnesses_to_outputs(
         """
         p2pk_signatures = await self.sign_p2pk_outputs(outputs)
         for o, s in zip(outputs, p2pk_signatures):
-            o.p2pksigs = [s]
+            o.witness = P2PKWitness(signatures=[s]).json()
         return outputs
 
     async def add_witnesses_to_outputs(