diff --git a/Lib/test/test_timeit.py b/Lib/test/test_timeit.py
index 5e9d49e..2db3c1b 100644
--- a/Lib/test/test_timeit.py
+++ b/Lib/test/test_timeit.py
@@ -88,8 +88,8 @@
         self.assertRaises(SyntaxError, timeit.Timer, setup='continue')
         self.assertRaises(SyntaxError, timeit.Timer, setup='from timeit import *')
 
-    fake_setup = "import timeit; timeit._fake_timer.setup()"
-    fake_stmt = "import timeit; timeit._fake_timer.inc()"
+    fake_setup = "import timeit\ntimeit._fake_timer.setup()"
+    fake_stmt = "import timeit\ntimeit._fake_timer.inc()"
 
     def fake_callable_setup(self):
         self.fake_timer.setup()
@@ -272,6 +272,12 @@
         self.assertEqual(s, "CustomSetup\n" * 3 +
                 "35 loops, best of 3: 2 sec per loop\n")
 
+    def test_main_multiple_setups(self):
+        s = self.run_main(seconds_per_increment=2.0,
+                switches=['-n35', '-s', 'a = "CustomSetup"', '-s', 'print(a)'])
+        self.assertEqual(s, "CustomSetup\n" * 3 +
+                "35 loops, best of 3: 2 sec per loop\n")
+
     def test_main_fixed_reps(self):
         s = self.run_main(seconds_per_increment=60.0, switches=['-r9'])
         self.assertEqual(s, "10 loops, best of 9: 60 sec per loop\n")
diff --git a/Lib/timeit.py b/Lib/timeit.py
index d9f9563..2de88f7 100755
--- a/Lib/timeit.py
+++ b/Lib/timeit.py
@@ -109,19 +109,18 @@
         if isinstance(setup, str):
             # Check that the code can be compiled outside a function
             compile(setup, dummy_src_name, "exec")
+            stmtprefix = setup + '\n'
             setup = reindent(setup, 4)
         elif callable(setup):
             local_ns['_setup'] = setup
             init += ', _setup=_setup'
+            stmtprefix = ''
             setup = '_setup()'
         else:
             raise ValueError("setup is neither a string nor callable")
         if isinstance(stmt, str):
             # Check that the code can be compiled outside a function
-            if isinstance(setup, str):
-                compile(setup + '\n' + stmt, dummy_src_name, "exec")
-            else:
-                compile(stmt, dummy_src_name, "exec")
+            compile(stmtprefix + stmt, dummy_src_name, "exec")
             stmt = reindent(stmt, 8)
         elif callable(stmt):
             local_ns['_stmt'] = stmt
diff --git a/Misc/NEWS b/Misc/NEWS
index 77c898c..bb7e04d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -17,6 +17,8 @@
 Library
 -------
 
+- Issue #24631: Fixed regression in the timeit modulu with multyline setup.
+
 - Issue #18622: unittest.mock.mock_open().reset_mock would recurse infinitely.
   Patch from Nicola Palumbo and Laurent De Buyst.