diff --git a/examples/basic_spot_to_perp.py b/examples/basic_spot_to_perp.py
index 95e9c34..c3a92cb 100644
--- a/examples/basic_spot_to_perp.py
+++ b/examples/basic_spot_to_perp.py
@@ -6,11 +6,11 @@ def main():
     address, info, exchange = example_utils.setup(constants.TESTNET_API_URL, skip_ws=True)
 
     # Transfer 1.23 USDC from perp wallet to spot wallet
-    transfer_result = exchange.user_spot_transfer(1.23, False)
+    transfer_result = exchange.usd_class_transfer(1.23, False)
     print(transfer_result)
 
     # Transfer 1.23 USDC from spot wallet to perp wallet
-    transfer_result = exchange.user_spot_transfer(1.23, True)
+    transfer_result = exchange.usd_class_transfer(1.23, True)
     print(transfer_result)
 
 
diff --git a/hyperliquid/exchange.py b/hyperliquid/exchange.py
index 1f79295..d9f5f53 100644
--- a/hyperliquid/exchange.py
+++ b/hyperliquid/exchange.py
@@ -55,7 +55,7 @@ def _post_action(self, action, signature, nonce):
             "action": action,
             "nonce": nonce,
             "signature": signature,
-            "vaultAddress": self.vault_address,
+            "vaultAddress": self.vault_address if action["type"] != "usdClassTransfer" else None,
         }
         logging.debug(payload)
         return self.post("/exchange", payload)
@@ -402,9 +402,13 @@ def create_sub_account(self, name: str) -> Any:
 
     def usd_class_transfer(self, amount: float, to_perp: bool) -> Any:
         timestamp = get_timestamp_ms()
+        str_amount = str(amount)
+        if self.vault_address:
+            str_amount += f" subaccount:{self.vault_address}"
+
         action = {
             "type": "usdClassTransfer",
-            "amount": str(amount),
+            "amount": str_amount,
             "toPerp": to_perp,
             "nonce": timestamp,
         }
diff --git a/pyproject.toml b/pyproject.toml
index 76e0c11..5eddc7b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "hyperliquid-python-sdk"
-version = "0.7.0"
+version = "0.7.1"
 description = "SDK for Hyperliquid API trading with Python."
 readme = "README.md"
 authors = ["Hyperliquid <hello@hyperliquid.xyz>"]