diff --git a/Lib/_pyrepl/commands.py b/Lib/_pyrepl/commands.py
index c3fce91013b001..f9992bf74eb4c3 100644
--- a/Lib/_pyrepl/commands.py
+++ b/Lib/_pyrepl/commands.py
@@ -282,7 +282,7 @@ def do(self) -> None:
             x, y = r.pos2xy()
             new_y = y + 1
 
-            if new_y > r.max_row():
+            if r.eol() == len(b):
                 if r.historyi < len(r.history):
                     r.select_item(r.historyi + 1)
                     r.pos = r.eol(0)
@@ -309,7 +309,7 @@ def do(self) -> None:
 class left(MotionCommand):
     def do(self) -> None:
         r = self.reader
-        for i in range(r.get_arg()):
+        for _ in range(r.get_arg()):
             p = r.pos - 1
             if p >= 0:
                 r.pos = p
@@ -321,7 +321,7 @@ class right(MotionCommand):
     def do(self) -> None:
         r = self.reader
         b = r.buffer
-        for i in range(r.get_arg()):
+        for _ in range(r.get_arg()):
             p = r.pos + 1
             if p <= len(b):
                 r.pos = p
diff --git a/Lib/_pyrepl/completing_reader.py b/Lib/_pyrepl/completing_reader.py
index e856bb9807c7f6..1cd4b6367ca8b1 100644
--- a/Lib/_pyrepl/completing_reader.py
+++ b/Lib/_pyrepl/completing_reader.py
@@ -260,10 +260,15 @@ def after_command(self, cmd: Command) -> None:
     def calc_screen(self) -> list[str]:
         screen = super().calc_screen()
         if self.cmpltn_menu_visible:
-            ly = self.lxy[1]
+            # We display the completions menu below the current prompt
+            ly = self.lxy[1] + 1
             screen[ly:ly] = self.cmpltn_menu
-            self.screeninfo[ly:ly] = [(0, [])]*len(self.cmpltn_menu)
-            self.cxy = self.cxy[0], self.cxy[1] + len(self.cmpltn_menu)
+            # If we're not in the middle of multiline edit, don't append to screeninfo
+            # since that screws up the position calculation in pos2xy function.
+            # This is a hack to prevent the cursor jumping
+            # into the completions menu when pressing left or down arrow.
+            if self.pos != len(self.buffer):
+                self.screeninfo[ly:ly] = [(0, [])]*len(self.cmpltn_menu)
         return screen
 
     def finish(self) -> None:
diff --git a/Lib/test/test_pyrepl/test_pyrepl.py b/Lib/test/test_pyrepl/test_pyrepl.py
index bbe19612437a1d..72e8b3517ffe80 100644
--- a/Lib/test/test_pyrepl/test_pyrepl.py
+++ b/Lib/test/test_pyrepl/test_pyrepl.py
@@ -850,7 +850,7 @@ def test_global_namespace_completion(self):
         output = multiline_input(reader, namespace)
         self.assertEqual(output, "python")
 
-    def test_updown_arrow_with_completion_menu(self):
+    def test_up_down_arrow_with_completion_menu(self):
         """Up arrow in the middle of unfinished tab completion when the menu is displayed
         should work and trigger going back in history. Down arrow should subsequently
         get us back to the incomplete command."""
@@ -860,6 +860,7 @@ def test_updown_arrow_with_completion_menu(self):
         events = itertools.chain(
             code_to_events(code),
             [
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
                 Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
                 Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
             ],
diff --git a/Lib/test/test_pyrepl/test_reader.py b/Lib/test/test_pyrepl/test_reader.py
index 6c72a1d39c55df..863ecc61ddd432 100644
--- a/Lib/test/test_pyrepl/test_reader.py
+++ b/Lib/test/test_pyrepl/test_reader.py
@@ -295,8 +295,8 @@ def test_completions_updated_on_key_press(self):
 
         actual = reader.screen
         self.assertEqual(len(actual), 2)
-        self.assertEqual(actual[0].rstrip(), "itertools.accumulate(")
-        self.assertEqual(actual[1], f"{code}a")
+        self.assertEqual(actual[0], f"{code}a")
+        self.assertEqual(actual[1].rstrip(), "itertools.accumulate(")
 
     def test_key_press_on_tab_press_once(self):
         namespace = {"itertools": itertools}
diff --git a/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst b/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst
new file mode 100644
index 00000000000000..8f3f863d93e021
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-07-14-23-19-20.gh-issue-119257.9OEzcN.rst
@@ -0,0 +1,2 @@
+Show tab completions menu below the current line, which results in less
+janky behaviour, and fixes a cursor movement bug. Patch by Daniel Hollas