diff --git a/electrum/gui/qt/main_window.py b/electrum/gui/qt/main_window.py
index e3ddbc6e6..7d1f0f5d6 100644
--- a/electrum/gui/qt/main_window.py
+++ b/electrum/gui/qt/main_window.py
@@ -1700,7 +1700,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
             return None
         return clayout.selected_index()
 
-    def lock_amount(self, b):
+    def lock_amount(self, b: bool) -> None:
         self.amount_e.setFrozen(b)
         self.max_button.setEnabled(not b)
 
diff --git a/electrum/gui/qt/paytoedit.py b/electrum/gui/qt/paytoedit.py
index 166907c61..9a2a6e69c 100644
--- a/electrum/gui/qt/paytoedit.py
+++ b/electrum/gui/qt/paytoedit.py
@@ -182,10 +182,10 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.payto_scriptpubkey = None
 
         if self.win.max_button.isChecked():
-            self.win.do_update_fee()
+            self.win.spend_max()
         else:
             self.amount_edit.setAmount(total if outputs else None)
-            self.win.lock_amount(total or len(lines)>1)
+        self.win.lock_amount(self.win.max_button.isChecked() or bool(outputs))
 
     def get_errors(self) -> Sequence[PayToLineError]:
         return self.errors