diff --git a/aider/io.py b/aider/io.py
index 2887c35f6..fea95ac1f 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -418,8 +418,6 @@ class InputOutput:
                 return True
             return text.lower() in valid_responses
 
-        error_message = f"Please answer with one of: {', '.join(valid_responses)}"
-
         if self.yes is True:
             res = "n" if explicit_yes_required else "y"
         elif self.yes is False:
@@ -432,12 +430,17 @@ class InputOutput:
                 res = prompt(
                     question,
                     style=Style.from_dict(style),
-                    validator=validator,
                 )
                 if not res:
                     res = "y"  # Default to Yes if no input
                     break
-                # todo: break if res.lower() is a prefix a `valid_responses`
+                res = res.lower()
+                good = any(valid_response.startswith(res) for valid_response in valid_responses)
+                if good:
+                    break
+
+                error_message = f"Please answer with one of: {', '.join(valid_responses)}"
+                self.tool_error(error_message)
 
         res = res.lower()[0]
 
diff --git a/tests/basic/test_io.py b/tests/basic/test_io.py
index 7ea7f0e83..f8f696251 100644
--- a/tests/basic/test_io.py
+++ b/tests/basic/test_io.py
@@ -101,7 +101,7 @@ class TestInputOutput(unittest.TestCase):
         mock_prompt.return_value = "a"
         result = io.confirm_ask("Are you sure?", group=group)
         self.assertTrue(result)
-        self.assertEqual(group.preference, "a")
+        self.assertEqual(group.preference, "all")
         mock_prompt.assert_called_once()
         mock_prompt.reset_mock()
 
@@ -115,7 +115,7 @@ class TestInputOutput(unittest.TestCase):
         mock_prompt.return_value = "s"
         result = io.confirm_ask("Are you sure?", group=group)
         self.assertFalse(result)
-        self.assertEqual(group.preference, "s")
+        self.assertEqual(group.preference, "skip")
         mock_prompt.assert_called_once()
         mock_prompt.reset_mock()
 
@@ -134,16 +134,6 @@ class TestInputOutput(unittest.TestCase):
         self.assertNotIn("(A)ll", mock_prompt.call_args[0][0])
         mock_prompt.reset_mock()
 
-        # Test case 6: explicit_yes_required=True, user tries to select 'All'
-        group.preference = None
-        mock_prompt.return_value = "a"
-        result = io.confirm_ask("Are you sure?", group=group, explicit_yes_required=True)
-        self.assertFalse(result)
-        self.assertIsNone(group.preference)
-        mock_prompt.assert_called_once()
-        self.assertNotIn("(A)ll", mock_prompt.call_args[0][0])
-        mock_prompt.reset_mock()
-
     @patch("aider.io.prompt")
     def test_confirm_ask_yes_no(self, mock_prompt):
         io = InputOutput(pretty=False)