diff --git a/electrum/coinchooser.py b/electrum/coinchooser.py
index f7ecffbe2..13787d45c 100644
--- a/electrum/coinchooser.py
+++ b/electrum/coinchooser.py
@@ -151,7 +151,7 @@ class CoinChooserBase(Logger):
     def penalty_func(self, base_tx, *, tx_from_buckets) -> Callable[[List[Bucket]], ScoredCandidate]:
         raise NotImplementedError
 
-    def _change_amounts(self, tx, count, fee_estimator_numchange):
+    def _change_amounts(self, tx, count, fee_estimator_numchange) -> List[int]:
         # Break change up if bigger than max_change
         output_amounts = [o.value for o in tx.outputs()]
         # Don't split change of less than 0.02 BTC
@@ -197,7 +197,7 @@ class CoinChooserBase(Logger):
         # no more than 10**max_dp_to_round_for_privacy
         # e.g. a max of 2 decimal places means losing 100 satoshis to fees
         max_dp_to_round_for_privacy = 2 if self.enable_output_value_rounding else 0
-        N = pow(10, min(max_dp_to_round_for_privacy, zeroes[0]))
+        N = int(pow(10, min(max_dp_to_round_for_privacy, zeroes[0])))
         amount = (remaining // N) * N
         amounts.append(amount)
 
@@ -209,6 +209,7 @@ class CoinChooserBase(Logger):
         amounts = self._change_amounts(tx, len(change_addrs), fee_estimator_numchange)
         assert min(amounts) >= 0
         assert len(change_addrs) >= len(amounts)
+        assert all([isinstance(amt, int) for amt in amounts])
         # If change is above dust threshold after accounting for the
         # size of the change output, add it to the transaction.
         amounts = [amount for amount in amounts if amount >= dust_threshold]
diff --git a/electrum/tests/test_wallet_vertical.py b/electrum/tests/test_wallet_vertical.py
index 6a80e1a60..f72edab51 100644
--- a/electrum/tests/test_wallet_vertical.py
+++ b/electrum/tests/test_wallet_vertical.py
@@ -896,7 +896,7 @@ class TestWalletSending(TestCaseForTestnet):
         self.assertEqual((0, funding_output_value - 2500000 - 5000, 0), wallet.get_balance())
 
         # bump tx
-        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70, config=self.config)
+        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70.0, config=self.config)
         tx.locktime = 1325501
         tx.version = 1
         self.assertFalse(tx.is_complete())
@@ -985,7 +985,7 @@ class TestWalletSending(TestCaseForTestnet):
         self.assertEqual((0, funding_output_value - 2500000 - 5000, 0), wallet.get_balance())
 
         # bump tx
-        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70, config=self.config)
+        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70.0, config=self.config)
         tx.locktime = 1325500
         tx.version = 1
         self.assertFalse(tx.is_complete())
@@ -1039,7 +1039,7 @@ class TestWalletSending(TestCaseForTestnet):
         self.assertEqual((0, 0, 0), wallet.get_balance())
 
         # bump tx
-        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70, config=self.config)
+        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70.0, config=self.config)
         tx.locktime = 1325500
         tx.version = 1
         self.assertFalse(tx.is_complete())
@@ -1102,7 +1102,7 @@ class TestWalletSending(TestCaseForTestnet):
         self.assertEqual((0, 5_000_000, 0), wallet.get_balance())
 
         # bump tx
-        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70, config=self.config)
+        tx = wallet.bump_fee(tx=Transaction(tx.serialize()), new_fee_rate=70.0, config=self.config)
         tx.locktime = 1325500
         tx.version = 1
         self.assertFalse(tx.is_complete())
diff --git a/electrum/transaction.py b/electrum/transaction.py
index 57753ca25..357f536a5 100644
--- a/electrum/transaction.py
+++ b/electrum/transaction.py
@@ -1039,13 +1039,13 @@ class Transaction:
         self.raw = None
         self.BIP69_sort(inputs=False)
 
-    def input_value(self):
+    def input_value(self) -> int:
         return sum(x['value'] for x in self.inputs())
 
-    def output_value(self):
+    def output_value(self) -> int:
         return sum(o.value for o in self.outputs())
 
-    def get_fee(self):
+    def get_fee(self) -> int:
         return self.input_value() - self.output_value()
 
     def is_final(self):
diff --git a/electrum/wallet.py b/electrum/wallet.py
index 2ef89efc3..12ad89d59 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -993,18 +993,20 @@ class Abstract_Wallet(AddressSynchronizer):
         # prioritize low value outputs, to get rid of dust
         s = sorted(s, key=lambda o: o.value)
         for o in s:
-            target_fee = tx.estimated_size() * new_fee_rate
+            target_fee = int(round(tx.estimated_size() * new_fee_rate))
             delta = target_fee - tx.get_fee()
             i = outputs.index(o)
             if o.value - delta >= self.dust_threshold():
-                outputs[i] = o._replace(value=o.value - delta)
+                new_output_value = o.value - delta
+                assert isinstance(new_output_value, int)
+                outputs[i] = o._replace(value=new_output_value)
                 delta = 0
                 break
             else:
                 del outputs[i]
                 delta -= o.value
-                if delta > 0:
-                    continue
+                # note: delta might be negative now, in which case
+                # the value of the next output will be increased
         if delta > 0:
             raise CannotBumpFee(_('Cannot bump fee') + ': ' + _('could not find suitable outputs'))