diff --git a/piggybank/piggybank.py b/piggybank/piggybank.py
index 902beff..a059b5f 100644
--- a/piggybank/piggybank.py
+++ b/piggybank/piggybank.py
@@ -18,11 +18,11 @@ class PiggyBank:
     .pb files."""
     def __init__(self, currency: str = DEFAULT_CURRENCY) -> None:
         if currency.upper() in CURRENCIES:
-            self.currency = currency.upper()
+            self._currency = currency.upper()
         else:
             raise CurrencyIsNotSupportedError
 
-        self.transactions = []
+        self._transactions = []
 
     def transact(self, coins: List[int], direction: str = TYPE_INCOME) -> None:
         """Make a transaction."""
@@ -31,11 +31,11 @@ class PiggyBank:
                              f"currency's coins count ({len(coins)} "
                              f"!= {CURRENCIES[self.currency]['count']})")
 
-        self.transactions.append(Transaction(coins, direction))
+        self._transactions.append(Transaction(coins, direction))
 
         for coin_count in self.count:
             if coin_count < 0:
-                del self.transactions[-1]
+                del self._transactions[-1]
                 raise ValueError(
                     "You can't take out more than you have.")
 
@@ -90,12 +90,12 @@ class PiggyBank:
             else:
                 self.currency = currency
             for transaction in _file:
-                self.transactions.append(Transaction.from_string(transaction))
+                self._transactions.append(Transaction.from_string(transaction))
 
     @property
     def currency(self) -> str:
         """Returns a currency of a PiggyBank."""
-        return self.currency
+        return self._currency
 
     @currency.setter
     def currency(self, currency: str) -> None:
@@ -106,12 +106,12 @@ class PiggyBank:
             raise CurrencyIsNotSupportedError
         if CURRENCIES[currency]["count"] != CURRENCIES[self.currency]["count"]:
             raise CurrenciesCoinCountMismatchError
-        self.currency = currency
+        self._currency = currency
 
     @property
     def transactions(self) -> List[Transaction]:
         """Returns a list of transactions."""
-        return self.transactions
+        return self._transactions
 
     def __eq__(self, piggybank: PiggyBank) -> str:
         """It compares only currency."""