diff --git a/pw_cli/py/pw_cli/env.py b/pw_cli/py/pw_cli/env.py
index 41f16f3..dc9eaa7 100644
--- a/pw_cli/py/pw_cli/env.py
+++ b/pw_cli/py/pw_cli/env.py
@@ -40,9 +40,7 @@
     parser.add_var('PW_USE_COLOR', type=envparse.strict_bool, default=False)
     parser.add_var('PW_USE_GCS_ENVSETUP', type=envparse.strict_bool)
 
-    parser.add_var('PW_PIGWEED_CIPD_INSTALL_DIR')
-    parser.add_var('PW_LUCI_CIPD_INSTALL_DIR')
-    parser.add_var('PW_CIPD_INSTALL_DIR')
+    parser.add_allowed_suffix('_CIPD_INSTALL_DIR')
 
     parser.add_var('PW_CIPD_PACKAGE_FILES')
     parser.add_var('PW_VIRTUALENV_REQUIREMENTS')
diff --git a/pw_cli/py/pw_cli/envparse.py b/pw_cli/py/pw_cli/envparse.py
index c65330b..2450992 100644
--- a/pw_cli/py/pw_cli/envparse.py
+++ b/pw_cli/py/pw_cli/envparse.py
@@ -15,8 +15,8 @@
 
 import argparse
 import os
-from typing import Callable, Dict, Generic, IO, Literal, Mapping, NamedTuple
-from typing import Optional, TypeVar
+from typing import Callable, Dict, Generic, IO, List, Literal, Mapping
+from typing import NamedTuple, Optional, TypeVar
 
 
 class EnvNamespace(argparse.Namespace):  # pylint: disable=too-few-public-methods
@@ -73,6 +73,7 @@
         self._prefix: Optional[str] = prefix
         self._error_on_unrecognized: bool = error_on_unrecognized
         self._variables: Dict[str, VariableDescriptor] = {}
+        self._allowed_suffixes: List[str] = []
 
     def add_var(
         self,
@@ -102,6 +103,11 @@
             type,  # type: ignore
             default)  # type: ignore
 
+    def add_allowed_suffix(self, suffix: str) -> None:
+        """Registers an environmant variable name suffix to be allowed."""
+
+        self._allowed_suffixes.append(suffix)
+
     def parse_env(self,
                   env: Optional[Mapping[str, str]] = None) -> EnvNamespace:
         """Parses known environment variables into a namespace.
@@ -128,9 +134,17 @@
 
             setattr(namespace, var, val)
 
+        allowed_suffixes = tuple(self._allowed_suffixes)
+        for var in env:
+            if (not hasattr(namespace, var)
+                    and (self._prefix is None or var.startswith(self._prefix))
+                    and var.endswith(allowed_suffixes)):
+                setattr(namespace, var, env[var])
+
         if self._prefix is not None and self._error_on_unrecognized:
             for var in env:
-                if var.startswith(self._prefix) and var not in self._variables:
+                if (var.startswith(self._prefix) and var not in self._variables
+                        and not var.endswith(allowed_suffixes)):
                     raise ValueError(
                         f'Unrecognized environment variable {var}')
 
diff --git a/pw_cli/py/pw_cli/envparse_test.py b/pw_cli/py/pw_cli/envparse_test.py
index 8917a42..0a6f180 100644
--- a/pw_cli/py/pw_cli/envparse_test.py
+++ b/pw_cli/py/pw_cli/envparse_test.py
@@ -96,6 +96,7 @@
             'PW_FOO': '001',
             'PW_BAR': '010',
             'PW_BAZ': '100',
+            'IGNORED': '011',
         }
 
     def test_parse_unrecognized_variable(self):
@@ -106,6 +107,20 @@
         with self.assertRaises(ValueError):
             parser.parse_env(env=self.raw_env)
 
+    def test_parse_unrecognized_but_allowed_suffix(self):
+        parser = envparse.EnvironmentParser(prefix='PW_')
+        parser.add_allowed_suffix('_ALLOWED_SUFFIX')
+
+        env = parser.parse_env(env={'PW_FOO_ALLOWED_SUFFIX': '001'})
+        self.assertEqual(env.PW_FOO_ALLOWED_SUFFIX, '001')
+
+    def test_parse_allowed_suffix_but_not_suffix(self):
+        parser = envparse.EnvironmentParser(prefix='PW_')
+        parser.add_allowed_suffix('_ALLOWED_SUFFIX')
+
+        with self.assertRaises(ValueError):
+            parser.parse_env(env={'PW_FOO_ALLOWED_SUFFIX_FOO': '001'})
+
     def test_parse_ignore_unrecognized(self):
         parser = envparse.EnvironmentParser(prefix='PW_',
                                             error_on_unrecognized=False)