diff --git a/setup.py b/setup.py
index de3ed4f..5a2d766 100644
--- a/setup.py
+++ b/setup.py
@@ -1,10 +1,14 @@
+## setup.py file for roicat
 from pathlib import Path
+import copy
+import platform
 
 from distutils.core import setup
-import copy
 
+## Get the parent directory of this file
 dir_parent = Path(__file__).parent
 
+## Get requirements from requirements.txt
 def read_requirements():
     with open(str(dir_parent / "requirements.txt"), "r") as req:
         content = req.read()  ## read the file
@@ -18,14 +22,24 @@ def read_requirements():
     requirements = [req.replace(",", "").replace("\"", "").replace("\'", "").strip() for req in requirements]
 
     return requirements
-
 deps_all = read_requirements()
 
+
 ## Dependencies: latest versions of requirements
 ### remove everything starting and after the first =,>,<,! sign
 deps_names = [req.split('=')[0].split('>')[0].split('<')[0].split('!')[0] for req in deps_all]
 deps_all_dict = dict(zip(deps_names, deps_all))
-deps_all_latest = copy.deepcopy(deps_names)
+deps_all_latest = dict(zip(deps_names, deps_names))
+
+
+## Operating system specific dependencies
+### OpenCV >= 4.9 is not supported on macOS < 12
+system, version = platform.system(), platform.mac_ver()[0]
+if system == "Darwin" and version and ('opencv_contrib_python' in deps_all_dict):
+    if tuple(map(int, version.split('.'))) < (12, 0, 0):
+        version_opencv_macosSub12 = "opencv_contrib_python<=4.8.1.78"
+        deps_all_dict['opencv_contrib_python'], deps_all_latest['opencv_contrib_python'] = version_opencv_macosSub12, version_opencv_macosSub12
+
 
 ## Make different versions of dependencies
 ### Also pull out the version number from the requirements (specified in deps_all_dict values).