diff -Naur nanopb/CMakeLists.txt nanopb-fix/CMakeLists.txt
--- nanopb/CMakeLists.txt	2021-03-22 08:50:07.000000000 -0400
+++ nanopb-fix/CMakeLists.txt	2022-06-24 16:17:09.130783413 -0400
@@ -41,7 +41,7 @@
 if(nanopb_BUILD_GENERATOR)
     set(generator_protos nanopb plugin)
 
-    find_package(PythonInterp 2.7 REQUIRED)
+    find_package(PythonInterp 3.7 REQUIRED)
     execute_process(
         COMMAND ${PYTHON_EXECUTABLE} -c
             "from distutils import sysconfig; print(sysconfig.get_python_lib(prefix=''))"
diff -Naur nanopb/generator/nanopb_generator.py nanopb-fix/generator/nanopb_generator.py
--- nanopb/generator/nanopb_generator.py	2021-03-22 08:50:07.000000000 -0400
+++ nanopb-fix/generator/nanopb_generator.py	2022-11-01 15:37:38.112297044 -0400
@@ -1641,7 +1641,9 @@
             optfilename = os.path.join(p, optfilename)
             if options.verbose:
                 sys.stderr.write('Reading options from ' + optfilename + '\n')
-            Globals.separate_options = read_options_file(open(optfilename, "rU"))
+            # Patch in https://github.com/nanopb/nanopb/commit/01e9186a8b to avoid
+            # using "U" in the filemode, whose support was removed in Python 3.11.
+            Globals.separate_options = read_options_file(open(optfilename, 'r', encoding = 'utf-8'))
             break
     else:
         # If we are given a full filename and it does not exist, give an error.