diff --git a/cmake_support/PROMOD3.cmake b/cmake_support/PROMOD3.cmake
index 01f5f74ccc169f108467bf5cf2483c3f063f6de8..43c58be4527a8f84c55ac60c6111741ad5318c53 100644
--- a/cmake_support/PROMOD3.cmake
+++ b/cmake_support/PROMOD3.cmake
@@ -990,6 +990,9 @@ endfunction(get_compiler_version)
 
 
 macro(setup_compiler_flags)
+  if("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+  endif()
   if(CMAKE_COMPILER_IS_GNUCXX)
     get_compiler_version(_GCC_VERSION)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall" )
diff --git a/core/tests/test_pm3argparse.py b/core/tests/test_pm3argparse.py
index d5c195987db76ce960be7370fc8d236f081fea6e..ab5270deb4ca0bf7209a2d3836e074a8400496fb 100644
--- a/core/tests/test_pm3argparse.py
+++ b/core/tests/test_pm3argparse.py
@@ -22,6 +22,7 @@ import unittest
 import tempfile
 import gzip
 import json
+import sys
 import ost
 from promod3.core import pm3argparse
 
@@ -89,22 +90,35 @@ class PM3ArgParseTests(unittest.TestCase):
         with self.assertRaises(SystemExit) as ecd:
             parser.Parse(['--help'])
         self.assertEqual(ecd.exception.code, 0)
-        self.assertEqual(self.log.messages['SCRIPT'],
-                         ['usage: test_pm3argparse.py [-h]\n\nTesting our '+
-                          'own little argument parser.\n\noptional '+
-                          'arguments:\n  -h, --help  show this help message '+
-                          'and exit'])
+        self.assertEqual(ecd.exception.code, 0)
+        if sys.version_info >= (3,11):
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: test_pm3argparse.py [-h]\n\nTesting our '+
+                              'own little argument parser.\n\noptions:\n  -h, '+
+                              '--help  show this help message and exit'])
+        else:
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: test_pm3argparse.py [-h]\n\nTesting our '+
+                              'own little argument parser.\n\noptional '+
+                              'arguments:\n  -h, --help  show this help '+
+                              'message and exit'])
 
         self.log.messages = dict()
         parser = pm3argparse.PM3ArgumentParser(__doc__, action=True)
         with self.assertRaises(SystemExit) as ecd:
             parser.Parse(['--help'])
         self.assertEqual(ecd.exception.code, 0)
-        self.assertEqual(self.log.messages['SCRIPT'],
-                         ['usage: t_pm3argparse.py [-h]\n\nTesting our own '+
-                          'little argument parser.\n\noptional '+
-                          'arguments:\n  -h, --help  show this help message '+
-                          'and exit'])
+        if sys.version_info >= (3,11):
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: t_pm3argparse.py [-h]\n\nTesting our '+
+                              'own little argument parser.\n\noptions:\n  '+
+                              '-h, --help  show this help message and exit'])
+        else:
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: t_pm3argparse.py [-h]\n\nTesting our '+
+                              'own little argument parser.\n\noptional '+
+                              'arguments:\n  -h, --help  show this help '+
+                              'message and exit'])
 
 
     def testDescription(self):
@@ -113,10 +127,16 @@ class PM3ArgParseTests(unittest.TestCase):
         with self.assertRaises(SystemExit) as ecd:
             parser.Parse(['--help'])
         self.assertEqual(ecd.exception.code, 0)
-        self.assertEqual(self.log.messages['SCRIPT'],
-                         ['usage: test_pm3argparse.py [-h]\n\nThis is a '+
-                          'test.\n\noptional arguments:\n  -h, --help  show '+
-                          'this help message and exit'])
+        if sys.version_info >= (3,11):
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: test_pm3argparse.py [-h]\n\nThis is a '+
+                              'test.\n\noptions:\n  -h, --help  '+
+                              'show this help message and exit'])
+        else:
+            self.assertEqual(self.log.messages['SCRIPT'],
+                             ['usage: test_pm3argparse.py [-h]\n\nThis is a '+
+                              'test.\n\noptional arguments:\n  -h, --help  '+
+                              'show this help message and exit'])
 
     def testAddAlignmentNoFileArg(self):
         # check failure on missing file argument