diff --git a/test/common.py b/test/common.py
index 8f2ba6bdb312c..1b5444cb2288a 100644
--- a/test/common.py
+++ b/test/common.py
@@ -491,7 +491,7 @@ def require_node_25(self):
     if not nodejs:
       self.skipTest('Test requires nodejs to run')
     if not self.try_require_node_version(25, 0, 0):
-      if os.getenv('EMTEST_AUTOSKIP') == '1':
+      if utils.get_env_bool('EMTEST_AUTOSKIP'):
         self.skipTest('test requires node v25 and current Node.js version is older than this, with EMTEST_AUTOSKIP being set')
       self.fail('node v25 required to run this test.  Use EMTEST_SKIP_NODE_25 to skip')
 
diff --git a/test/runner.py b/test/runner.py
index d3d6a7110b51f..7bdde5e96945b 100755
--- a/test/runner.py
+++ b/test/runner.py
@@ -457,7 +457,7 @@ def flattened_tests(loaded_tests):
 
 def run_tests(options, suite):
   # Run the discovered tests
-  if os.getenv('CI'):
+  if utils.get_env_bool('CI'):
     # output fd must remain open until after testRunner.run() below
     output = open('out/test-results.xml', 'wb')
     import xmlrunner  # type: ignore  # noqa: PLC0415
@@ -552,16 +552,16 @@ def parse_args():
 
 def configure():
   browser_common.EMTEST_BROWSER = os.getenv('EMTEST_BROWSER')
-  browser_common.EMTEST_BROWSER_AUTO_CONFIG = int(os.getenv('EMTEST_BROWSER_AUTO_CONFIG', '1'))
-  browser_common.EMTEST_HEADLESS = int(os.getenv('EMTEST_HEADLESS', '0'))
-  common.EMTEST_DETECT_TEMPFILE_LEAKS = int(os.getenv('EMTEST_DETECT_TEMPFILE_LEAKS', '0'))
-  common.EMTEST_ALL_ENGINES = int(os.getenv('EMTEST_ALL_ENGINES', '0'))
-  common.EMTEST_SKIP_SLOW = int(os.getenv('EMTEST_SKIP_SLOW', '0'))
-  common.EMTEST_SKIP_FLAKY = int(os.getenv('EMTEST_SKIP_FLAKY', '0'))
-  common.EMTEST_RETRY_FLAKY = int(os.getenv('EMTEST_RETRY_FLAKY', '0'))
-  common.EMTEST_LACKS_NATIVE_CLANG = int(os.getenv('EMTEST_LACKS_NATIVE_CLANG', '0'))
-  common.EMTEST_REBASELINE = int(os.getenv('EMTEST_REBASELINE', '0'))
-  common.EMTEST_VERBOSE = int(os.getenv('EMTEST_VERBOSE', '0')) or shared.DEBUG
+  browser_common.EMTEST_BROWSER_AUTO_CONFIG = utils.get_env_bool('EMTEST_BROWSER_AUTO_CONFIG', '1')
+  browser_common.EMTEST_HEADLESS = utils.get_env_bool('EMTEST_HEADLESS')
+  common.EMTEST_DETECT_TEMPFILE_LEAKS = utils.get_env_bool('EMTEST_DETECT_TEMPFILE_LEAKS')
+  common.EMTEST_ALL_ENGINES = utils.get_env_bool('EMTEST_ALL_ENGINES')
+  common.EMTEST_SKIP_SLOW = utils.get_env_bool('EMTEST_SKIP_SLOW')
+  common.EMTEST_SKIP_FLAKY = utils.get_env_bool('EMTEST_SKIP_FLAKY')
+  common.EMTEST_RETRY_FLAKY = utils.get_env_int('EMTEST_RETRY_FLAKY')
+  common.EMTEST_LACKS_NATIVE_CLANG = utils.get_env_bool('EMTEST_LACKS_NATIVE_CLANG')
+  common.EMTEST_REBASELINE = utils.get_env_bool('EMTEST_REBASELINE')
+  common.EMTEST_VERBOSE = utils.get_env_bool('EMTEST_VERBOSE') or shared.DEBUG
   if common.EMTEST_VERBOSE:
     logging.root.setLevel(logging.DEBUG)
 
diff --git a/test/test_browser.py b/test/test_browser.py
index bf935ec74a483..46fb9fae67c8e 100644
--- a/test/test_browser.py
+++ b/test/test_browser.py
@@ -286,7 +286,7 @@ def make_reftest(self, expected):
     #   pngcrush -rem gAMA -rem cHRM -rem iCCP -rem sRGB infile outfile
     shutil.copy(expected, 'expected.png')
     create_file('reftest.js', f'''
-      const reftestRebaseline = {common.EMTEST_REBASELINE};
+      const reftestRebaseline = {int(common.EMTEST_REBASELINE)};
     ''' + read_file(test_file('reftest.js')))
 
   def reftest(self, filename, reference=None, reference_slack=0, *args, **kwargs):
@@ -308,7 +308,7 @@ def reftest(self, filename, reference=None, reference_slack=0, *args, **kwargs):
         self.run_process('pngcrush -rem gAMA -rem cHRM -rem iCCP -rem sRGB actual.png'.split() + [reference])
 
   def test_sdl1_in_emscripten_nonstrict_mode(self):
-    if 'EMCC_STRICT' in os.environ and int(os.environ['EMCC_STRICT']):
+    if utils.get_env_bool('EMCC_STRICT'):
       self.skipTest('This test requires being run in non-strict mode (EMCC_STRICT env. variable unset)')
     # TODO: This test is verifying behavior that will be deprecated at some point in the future, remove this test once
     # system JS libraries are no longer automatically linked to anymore.
diff --git a/tools/response_file.py b/tools/response_file.py
index 805e8c3f8d949..b33a407723df8 100644
--- a/tools/response_file.py
+++ b/tools/response_file.py
@@ -9,9 +9,9 @@
 import tempfile
 
 from . import shared
-from .utils import WINDOWS
+from .utils import WINDOWS, get_env_int
 
-DEBUG = int(os.environ.get('EMCC_DEBUG', '0'))
+DEBUG = get_env_int('EMCC_DEBUG')
 
 
 def create_response_file_contents(args):
diff --git a/tools/settings.py b/tools/settings.py
index 77f33b0758b3a..169d2719638dd 100644
--- a/tools/settings.py
+++ b/tools/settings.py
@@ -5,7 +5,6 @@
 
 import copy
 import difflib
-import os
 import re
 from typing import Any
 
@@ -300,9 +299,7 @@ def read_js_settings(filename, attrs):
     self.attrs.update(internal_attrs)
     self.infer_types()
 
-    strict_override = False
-    if 'EMCC_STRICT' in os.environ:
-      strict_override = int(os.environ.get('EMCC_STRICT'))
+    strict_override = utils.get_env_bool('EMCC_STRICT')
 
     # Special handling for LEGACY_SETTINGS.  See src/setting.js for more
     # details
diff --git a/tools/shared.py b/tools/shared.py
index efa6ce35a5942..f4b80ee123f08 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -24,11 +24,20 @@
 assert sys.version_info >= (3, 10), f'emscripten requires python 3.10 or above ({sys.executable} {sys.version})'
 
 from . import colored_logger
+from .utils import (
+  exe_path_from_root,
+  exit_with_error,
+  get_env_bool,
+  get_env_int,
+  memoize,
+  path_from_root,
+  safe_ensure_dirs,
+)
 
 # Configure logging before importing any other local modules so even
 # log message during import are shown as expected.
-DEBUG = int(os.environ.get('EMCC_DEBUG', '0'))
-EMCC_LOGGING = int(os.environ.get('EMCC_LOGGING', '1'))
+DEBUG = get_env_int('EMCC_DEBUG')
+EMCC_LOGGING = get_env_bool('EMCC_LOGGING', '1')
 log_level = logging.ERROR
 if DEBUG:
   log_level = logging.DEBUG
@@ -42,10 +51,9 @@
 
 from . import cache, config, diagnostics, filelock, tempfiles, utils
 from .settings import settings
-from .utils import exe_path_from_root, exit_with_error, memoize, path_from_root, safe_ensure_dirs
 
-DEBUG_SAVE = DEBUG or int(os.environ.get('EMCC_DEBUG_SAVE', '0'))
-PRINT_SUBPROCS = int(os.getenv('EMCC_VERBOSE', '0'))
+DEBUG_SAVE = DEBUG or get_env_bool('EMCC_DEBUG_SAVE')
+PRINT_SUBPROCS = get_env_bool('EMCC_VERBOSE')
 SKIP_SUBPROCS = False
 
 # Minimum node version required to run the emscripten compiler.  This is
@@ -347,7 +355,7 @@ def perform_sanity_checks(quiet=False):
 
   llvm_ok = check_llvm()
 
-  if os.environ.get('EM_IGNORE_SANITY'):
+  if utils.get_env_bool('EM_IGNORE_SANITY'):
     logger.info('EM_IGNORE_SANITY set, ignoring sanity checks')
     return
 
@@ -374,7 +382,7 @@ def check_sanity(force=False, quiet=False):
   EM_CONFIG (so, we re-check sanity when the settings are changed).  We also
   re-check sanity and clear the cache when the version changes.
   """
-  if not force and os.environ.get('EMCC_SKIP_SANITY_CHECK') == '1':
+  if not force and utils.get_env_bool('EMCC_SKIP_SANITY_CHECK'):
     return
 
   # We set EMCC_SKIP_SANITY_CHECK so that any subprocesses that we launch will
@@ -391,7 +399,7 @@ def check_sanity(force=False, quiet=False):
       perform_sanity_checks(quiet)
     return
 
-  if os.environ.get('EM_IGNORE_SANITY'):
+  if utils.get_env_bool('EM_IGNORE_SANITY'):
     perform_sanity_checks(quiet)
     return
 
@@ -498,7 +506,7 @@ def setup_temp_dirs():
   global EMSCRIPTEN_TEMP_DIR, CANONICAL_TEMP_DIR, TEMP_DIR
   EMSCRIPTEN_TEMP_DIR = None
 
-  TEMP_DIR = os.environ.get("EMCC_TEMP_DIR", tempfile.gettempdir())
+  TEMP_DIR = os.environ.get('EMCC_TEMP_DIR', tempfile.gettempdir())
   if not os.path.isdir(TEMP_DIR):
     exit_with_error(f'The temporary directory `{TEMP_DIR}` does not exist! Please make sure that the path is correct.')
 
diff --git a/tools/system_libs.py b/tools/system_libs.py
index 667dbee0f8920..85dfc7b202ff1 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -18,7 +18,7 @@
 from . import building, cache, diagnostics, shared, utils
 from .settings import settings
 from .toolchain_profiler import ToolchainProfiler
-from .utils import read_file
+from .utils import get_env_bool, read_file
 
 logger = logging.getLogger('system_libs')
 
@@ -37,7 +37,7 @@
 #
 # Setting EMCC_USE_NINJA=2 means that ninja will automatically be run for each library needed at
 # link time.
-USE_NINJA = int(os.environ.get('EMCC_USE_NINJA', '0'))
+USE_NINJA = get_env_bool('EMCC_USE_NINJA')
 
 # A (fake) deterministic emscripten path to use in __FILE__ macro and debug info
 # to produce reproducible builds across platforms.
@@ -487,7 +487,7 @@ def build_objects(self, build_dir):
     By default, this builds all the source files returned by `self.get_files()`,
     with the `cflags` returned by `self.get_cflags()`.
     """
-    batch_inputs = int(os.environ.get('EMCC_BATCH_BUILD', '1'))
+    batch_inputs = get_env_bool('EMCC_BATCH_BUILD', '1')
     self.build_dir = build_dir
     batches = {}
     commands = []
@@ -1477,7 +1477,7 @@ def can_use(self):
     # In both cases, the build is not one that is hyper-focused on code size,
     # and so optz is not that important.
     return super().can_use() and settings.SHRINK_LEVEL >= 2 and \
-        not settings.LINKABLE and not os.environ.get('EMCC_FORCE_STDLIBS')
+        not settings.LINKABLE and 'EMCC_FORCE_STDLIBS' not in os.environ
 
 
 class libprintf_long_double(libc):
@@ -2319,14 +2319,14 @@ def get_libs_to_link(options):
   # avoids spending time checking for unresolved symbols in your project files,
   # which can speed up linking, but if you do not have the proper list of
   # actually needed libraries, errors can occur.
-  only_forced = os.environ.get('EMCC_ONLY_FORCED_STDLIBS')
+  only_forced = utils.get_env_bool('EMCC_ONLY_FORCED_STDLIBS')
   if only_forced:
     # One of the purposes EMCC_ONLY_FORCED_STDLIBS was to skip the scanning
     # of the input files for reverse dependencies.
     diagnostics.warning('deprecated', 'EMCC_ONLY_FORCED_STDLIBS is deprecated.  Use `-nostdlib` to avoid linking standard libraries')
   if force == '1':
     force_include = [name for name, lib in system_libs_map.items() if not lib.never_force]
-  elif force is not None:
+  elif force:
     force_include = force.split(',')
   if force_include:
     logger.debug(f'forcing stdlibs: {force_include}')
@@ -2412,8 +2412,7 @@ def add_sanitizer_libs():
   if settings.PRINTF_LONG_DOUBLE:
     add_library('libprintf_long_double')
   # See comment in libc_optz itself
-  if settings.SHRINK_LEVEL >= 2 and not settings.LINKABLE and \
-     not os.environ.get('EMCC_FORCE_STDLIBS'):
+  if settings.SHRINK_LEVEL >= 2 and not settings.LINKABLE and not force:
     add_library('libc_optz')
   if settings.STANDALONE_WASM:
     add_library('libstandalonewasm')
diff --git a/tools/utils.py b/tools/utils.py
index 9e80c400d7522..6d1f3d29a8262 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -48,6 +48,17 @@ def run_process(cmd, check=True, input=None, *args, **kw):
   return ret
 
 
+def get_env_bool(name, default='0'):
+  env_var = os.getenv(name, default)
+  assert env_var in {'true', 'false', '1', '0'}, f'invalid environment variable setting {env_var} for {name}'
+  return env_var in {'1', 'true'}
+
+
+def get_env_int(name, default=0):
+  env_var = os.getenv(name, default)
+  return int(env_var)
+
+
 def exec(cmd):
   if WINDOWS:
     rtn = run_process(cmd, stdin=sys.stdin, check=False).returncode
@@ -221,7 +232,7 @@ def get_num_cores():
     cpu_count = len(os.sched_getaffinity(0))
   else:
     cpu_count = os.cpu_count()
-  return int(os.environ.get('EMCC_CORES', cpu_count))
+  return get_env_int('EMCC_CORES', cpu_count)
 
 
 memoize = functools.cache