diff --git a/distutils/command/build_py.py b/distutils/command/build_py.py
index a20b076f..d2a4fd12 100644
--- a/distutils/command/build_py.py
+++ b/distutils/command/build_py.py
@@ -360,6 +360,10 @@ def build_modules(self) -> None:
             self.build_module(module, module_file, package)
 
     def build_packages(self) -> None:
+        if self.packages is None:
+            raise TypeError(
+                f"{type(self).__name__}.packages is None. Is the Distribution missing packages ?"
+            )
         for package in self.packages:
             # Get list of (package, module, module_file) tuples based on
             # scanning the package directory.  'package' is only included
diff --git a/distutils/compilers/C/base.py b/distutils/compilers/C/base.py
index 93385e13..8128b483 100644
--- a/distutils/compilers/C/base.py
+++ b/distutils/compilers/C/base.py
@@ -70,7 +70,7 @@ class Compiler:
     # dictionary (see below -- used by the 'new_compiler()' factory
     # function) -- authors of new compiler interface classes are
     # responsible for updating 'compiler_class'!
-    compiler_type: ClassVar[str] = None  # type: ignore[assignment]
+    compiler_type: ClassVar[str] = None  # pyright: ignore[reportAssignmentType]
 
     # XXX things not handled by this compiler abstraction model:
     #   * client can't provide additional options for a compiler,
diff --git a/distutils/dist.py b/distutils/dist.py
index b9552a8b..90101e37 100644
--- a/distutils/dist.py
+++ b/distutils/dist.py
@@ -1198,7 +1198,7 @@ def _read_list(name):
         self.description = _read_field('summary')
 
         if 'keywords' in msg:
-            self.keywords = _read_field('keywords').split(',')
+            self.keywords = _read_field('keywords').split(',')  # type:ignore[union-attr] # Manually checked
 
         self.platforms = _read_list('platform')
         self.classifiers = _read_list('classifier')
diff --git a/distutils/filelist.py b/distutils/filelist.py
index 70dc0fde..628cbb4f 100644
--- a/distutils/filelist.py
+++ b/distutils/filelist.py
@@ -261,6 +261,7 @@ def include_pattern(
         # delayed loading of allfiles list
         if self.allfiles is None:
             self.findall()
+        assert self.allfiles is not None
 
         for name in self.allfiles:
             if pattern_re.search(name):
diff --git a/distutils/sysconfig.py b/distutils/sysconfig.py
index 7ddc869a..fe2d3270 100644
--- a/distutils/sysconfig.py
+++ b/distutils/sysconfig.py
@@ -324,6 +324,16 @@ def customize_compiler(compiler: CCompiler) -> None:
             'AR',
             'ARFLAGS',
         )
+        assert isinstance(cc, str)
+        assert isinstance(cxx, str)
+        assert isinstance(cflags, str)
+        assert isinstance(ccshared, str)
+        assert isinstance(ldshared, str)
+        assert isinstance(ldcxxshared, str)
+        assert isinstance(shlib_suffix, str)
+        assert isinstance(ar_flags, str)
+        ar = os.environ.get('AR', ar)
+        assert isinstance(ar, str)
 
         cxxflags = cflags
 
@@ -354,8 +364,6 @@ def customize_compiler(compiler: CCompiler) -> None:
         ldshared = _add_flags(ldshared, 'CPP')
         ldcxxshared = _add_flags(ldcxxshared, 'CPP')
 
-        ar = os.environ.get('AR', ar)
-
         archiver = ar + ' ' + os.environ.get('ARFLAGS', ar_flags)
         cc_cmd = cc + ' ' + cflags
         cxx_cmd = cxx + ' ' + cxxflags
diff --git a/distutils/util.py b/distutils/util.py
index 17e86fed..ffb41042 100644
--- a/distutils/util.py
+++ b/distutils/util.py
@@ -232,14 +232,9 @@ def grok_environment_error(exc: object, prefix: str = "error: ") -> str:
 
 
 # Needed by 'split_quoted()'
-_wordchars_re = _squote_re = _dquote_re = None
-
-
-def _init_regex():
-    global _wordchars_re, _squote_re, _dquote_re
-    _wordchars_re = re.compile(rf'[^\\\'\"{string.whitespace} ]*')
-    _squote_re = re.compile(r"'(?:[^'\\]|\\.)*'")
-    _dquote_re = re.compile(r'"(?:[^"\\]|\\.)*"')
+_wordchars_re = re.compile(rf'[^\\\'\"{string.whitespace} ]*')
+_squote_re = re.compile(r"'(?:[^'\\]|\\.)*'")
+_dquote_re = re.compile(r'"(?:[^"\\]|\\.)*"')
 
 
 def split_quoted(s: str) -> list[str]:
@@ -256,8 +251,6 @@ def split_quoted(s: str) -> list[str]:
     # This is a nice algorithm for splitting up a single string, since it
     # doesn't require character-by-character examination.  It was a little
     # bit of a brain-bender to get it working right, though...
-    if _wordchars_re is None:
-        _init_regex()
 
     s = s.strip()
     words = []
@@ -265,6 +258,7 @@ def split_quoted(s: str) -> list[str]:
 
     while s:
         m = _wordchars_re.match(s, pos)
+        assert m is not None
         end = m.end()
         if end == len(s):
             words.append(s[:end])
@@ -305,9 +299,6 @@ def split_quoted(s: str) -> list[str]:
     return words
 
 
-# split_quoted ()
-
-
 def execute(
     func: Callable[[Unpack[_Ts]], object],
     args: tuple[Unpack[_Ts]],
diff --git a/mypy.ini b/mypy.ini
index 146222a5..26b04200 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -16,20 +16,21 @@ disable_error_code =
 
 # local
 
+	# Code that is too dynamic using variable command names;
+	# and code that uses platform checks mypy doesn't understand
+	attr-defined,
+	# These reveal issues in distutils/_modified.py that should be fixed
+	return-value,
+	type-var,
 	# TODO: Resolve and re-enable these gradually
 	operator,
-	attr-defined,
 	arg-type,
 	assignment,
 	call-overload,
-	return-value,
 	index,
-	type-var,
 	func-returns-value,
-	union-attr,
 	str-bytes-safe,
 	misc,
-	has-type,
 
 # stdlib's test module is not typed on typeshed
 [mypy-test.*]