diff --git a/micromamba/tests/test_config.py b/micromamba/tests/test_config.py
index 205c70b8d3..0e77d0bc74 100644
--- a/micromamba/tests/test_config.py
+++ b/micromamba/tests/test_config.py
@@ -68,6 +68,7 @@ def rc_file(
     tmp_prefix,
     tmp_path,
     user_config_dir,
+    monkeypatch,
 ):
     """Parametrizable fixture to create an rc file at the desired location.
 
@@ -85,7 +86,7 @@ def rc_file(
         elif where == "user_config_dir":
             rc_file = user_config_dir / rc_filename
         elif where == "env_set_xdg":
-            os.environ["XDG_CONFIG_HOME"] = str(tmp_home / "custom_xdg_config_dir")
+            monkeypatch.setenv("XDG_CONFIG_HOME", str(tmp_home / "custom_xdg_config_dir"))
             rc_file = tmp_home / "custom_xdg_config_dir" / "mamba" / rc_filename
         elif where == "absolute":
             rc_file = Path(rc_filename)
@@ -255,31 +256,27 @@ def test_list_with_groups(self, rc_file, group_flag):
             "  - channel1\n  - channel2\n".splitlines()
         )
 
-    def test_env_vars(self):
-        os.environ["MAMBA_OFFLINE"] = "true"
+    def test_env_vars(self, monkeypatch):
+        monkeypatch.setenv("MAMBA_OFFLINE", "true")
         assert (
             config("list", "offline", "--no-rc", "-s").splitlines()
             == "offline: true  # 'MAMBA_OFFLINE'".splitlines()
         )
 
-        os.environ["MAMBA_OFFLINE"] = "false"
+        monkeypatch.setenv("MAMBA_OFFLINE", "false")
         assert (
             config("list", "offline", "--no-rc", "-s").splitlines()
             == "offline: false  # 'MAMBA_OFFLINE'".splitlines()
         )
-        os.environ.pop("MAMBA_OFFLINE")
-
-    def test_no_env(self):
-        os.environ["MAMBA_OFFLINE"] = "false"
 
+    def test_no_env(self, monkeypatch):
+        monkeypatch.setenv("MAMBA_OFFLINE", "false")
         assert (
             config("list", "offline", "--no-rc", "--no-env", "-s", "--offline").splitlines()
             == "offline: true  # 'CLI'".splitlines()
         )
 
-        os.environ.pop("MAMBA_OFFLINE")
-
-    def test_precedence(self):
+    def test_precedence(self, monkeypatch):
         rc_dir = os.path.expanduser(os.path.join("~", "test_mamba", helpers.random_string()))
         os.makedirs(rc_dir, exist_ok=True)
         rc_file = os.path.join(rc_dir, ".mambarc")
@@ -289,15 +286,12 @@ def test_precedence(self):
             f.write("offline: true")
 
         try:
-            if "MAMBA_OFFLINE" in os.environ:
-                os.environ.pop("MAMBA_OFFLINE")
-
             assert (
                 config("list", "offline", f"--rc-file={rc_file}", "-s").splitlines()
                 == f"offline: true  # '{short_rc_file}'".splitlines()
             )
 
-            os.environ["MAMBA_OFFLINE"] = "false"
+            monkeypatch.setenv("MAMBA_OFFLINE", "false")
             assert (
                 config("list", "offline", "--no-rc", "-s").splitlines()
                 == "offline: false  # 'MAMBA_OFFLINE'".splitlines()
@@ -334,8 +328,6 @@ def test_precedence(self):
                 == "offline: true  # 'CLI'".splitlines()
             )
         finally:
-            if "MAMBA_OFFLINE" in os.environ:
-                os.environ.pop("MAMBA_OFFLINE")
             shutil.rmtree(os.path.expanduser(os.path.join("~", "test_mamba")))
 
 
diff --git a/micromamba/tests/test_create.py b/micromamba/tests/test_create.py
index 829960d508..3e9720e333 100644
--- a/micromamba/tests/test_create.py
+++ b/micromamba/tests/test_create.py
@@ -354,6 +354,7 @@ def test_target_prefix(
     similar_non_canonical,
     non_canonical_position,
     root_prefix_env_exists,
+    monkeypatch,
 ):
     cmd = []
 
@@ -412,12 +413,12 @@ def test_target_prefix(
         cmd += ["-f", spec_file]
 
     if env_var:
-        os.environ["MAMBA_TARGET_PREFIX"] = str(p)
+        monkeypatch.setenv("MAMBA_TARGET_PREFIX", str(p))
 
     if not current_target_prefix_fallback:
-        os.environ.pop("CONDA_PREFIX", None)
+        monkeypatch.delenv("CONDA_PREFIX", raising=False)
     else:
-        os.environ["CONDA_PREFIX"] = str(p)
+        monkeypatch.setenv("CONDA_PREFIX", str(p))
 
     if (
         (cli_prefix and cli_env_name)
@@ -436,7 +437,7 @@ def test_target_prefix(
 @pytest.mark.parametrize("yaml", (False, True))
 @pytest.mark.parametrize("env_var", (False, True))
 @pytest.mark.parametrize("rc_file", (False, True))
-def test_channels(tmp_home, tmp_root_prefix, tmp_path, cli, yaml, env_var, rc_file):
+def test_channels(tmp_home, tmp_root_prefix, tmp_path, cli, yaml, env_var, rc_file, monkeypatch):
     env_prefix = tmp_path / "myenv"
     spec_file = tmp_path / "env.yaml"
     rc_file = tmp_path / "rc.yaml"
@@ -460,7 +461,7 @@ def test_channels(tmp_home, tmp_root_prefix, tmp_path, cli, yaml, env_var, rc_fi
         expected_channels += ["yaml"]
 
     if env_var:
-        os.environ["CONDA_CHANNELS"] = "env_var"
+        monkeypatch.setenv("CONDA_CHANNELS", "env_var")
         expected_channels += ["env_var"]
 
     if rc_file:
@@ -682,9 +683,9 @@ def test_create_base(tmp_home, tmp_root_prefix, already_exists, is_conda_env, ha
     reason="Running only ultra-dry tests",
 )
 @pytest.mark.parametrize("outside_root_prefix", (False, True))
-def test_classic_specs(tmp_home, tmp_root_prefix, tmp_path, outside_root_prefix):
+def test_classic_specs(tmp_home, tmp_root_prefix, tmp_path, outside_root_prefix, monkeypatch):
     tmp_pkgs_dirs = tmp_path / "cache"
-    os.environ["CONDA_PKGS_DIRS"] = str(tmp_pkgs_dirs)
+    monkeypatch.setenv("CONDA_PKGS_DIRS", str(tmp_pkgs_dirs))
     if outside_root_prefix:
         p = tmp_path / "myenv"
     else:
@@ -1001,18 +1002,15 @@ def assert_env_exists(prefix_path):
 )
 @pytest.mark.parametrize("shared_pkgs_dirs", [True], indirect=True)
 @pytest.mark.parametrize("source", ["cli", "env_var", "rc_file"])
-def test_always_yes(tmp_home, tmp_root_prefix, tmp_path, source):
+def test_always_yes(tmp_home, tmp_root_prefix, tmp_path, source, monkeypatch):
     env_name = "myenv"
     helpers.create("-n", env_name, "xtensor", no_dry_run=True)
 
     if source == "cli":
         res = helpers.create("-n", env_name, "xtensor", "--json", always_yes=True)
     elif source == "env_var":
-        try:
-            os.environ["MAMBA_ALWAYS_YES"] = "true"
-            res = helpers.create("-n", env_name, "xtensor", "--json", always_yes=False)
-        finally:
-            os.environ.pop("MAMBA_ALWAYS_YES")
+        monkeypatch.setenv("MAMBA_ALWAYS_YES", "true")
+        res = helpers.create("-n", env_name, "xtensor", "--json", always_yes=False)
     else:  # rc_file
         rc_file = tmp_path / "config.yaml"
         with open(rc_file, "w") as f:
@@ -1150,7 +1148,7 @@ def test_spec_with_multichannel(tmp_home, tmp_root_prefix):
     helpers.create("-n", "myenv", "defaults::zlib", "--dry-run")
 
 
-def test_spec_with_slash_in_channel(tmp_home, tmp_root_prefix):
+def test_spec_with_slash_in_channel(tmp_home, tmp_root_prefix, monkeypatch):
     "https://github.com/mamba-org/mamba/pull/2926"
     with pytest.raises(subprocess.CalledProcessError) as info:
         helpers.create("-n", "env1", "pkgs/main/noarch::python", "--dry-run")
@@ -1161,7 +1159,7 @@ def test_spec_with_slash_in_channel(tmp_home, tmp_root_prefix):
         assert "The following package could not be installed" in msg
         assert "python" in msg
 
-    os.environ["CONDA_SUBDIR"] = "linux-64"
+    monkeypatch.setenv("CONDA_SUBDIR", "linux-64")
     helpers.create("-n", "env2", "pkgs/main/linux-64::python", "--dry-run")
     helpers.create("-n", "env3", "pkgs/main::python", "--dry-run")
 
diff --git a/micromamba/tests/test_env.py b/micromamba/tests/test_env.py
index 9c7ca2a3a6..623b613375 100644
--- a/micromamba/tests/test_env.py
+++ b/micromamba/tests/test_env.py
@@ -1,4 +1,3 @@
-import os
 import re
 import shutil
 
@@ -22,7 +21,7 @@ def test_env_list(tmp_home, tmp_root_prefix, tmp_empty_env):
     assert str(tmp_empty_env) in env_json["envs"]
 
 
-def test_env_list_table(tmp_home, tmp_root_prefix, tmp_prefix):
+def test_env_list_table(tmp_home, tmp_root_prefix, tmp_prefix, monkeypatch):
     res = helpers.run_env("list")
 
     assert "Name" in res
@@ -35,8 +34,6 @@ def test_env_list_table(tmp_home, tmp_root_prefix, tmp_prefix):
             active_env_l = line
     assert str(tmp_root_prefix) in active_env_l
 
-    os.environ["CONDA_PREFIX"] = str(tmp_prefix)
-
     res = helpers.run_env("list")
 
     all_lines = res.splitlines()
@@ -470,10 +467,10 @@ def test_env_create_whitespace(tmp_home, tmp_root_prefix, tmp_path):
 
 
 @pytest.mark.parametrize("shared_pkgs_dirs", [True], indirect=True)
-def test_env_update_empty_base(tmp_home, tmp_root_prefix, tmp_path):
+def test_env_update_empty_base(tmp_home, tmp_root_prefix, tmp_path, monkeypatch):
     env_prefix = tmp_path / "env-update-empty-base"
 
-    os.environ["MAMBA_ROOT_PREFIX"] = str(env_prefix)
+    monkeypatch.setenv("MAMBA_ROOT_PREFIX", str(env_prefix))
 
     env_file_yml = tmp_path / "test_env_empty_base.yaml"
     env_file_yml.write_text(env_yaml_content_to_update_empty_base)
diff --git a/micromamba/tests/test_info.py b/micromamba/tests/test_info.py
index 563571bb44..7d4a3610ea 100644
--- a/micromamba/tests/test_info.py
+++ b/micromamba/tests/test_info.py
@@ -40,7 +40,7 @@ def test_env(tmp_home, tmp_root_prefix, tmp_env_name, tmp_prefix, prefix_selecti
 
 @pytest.mark.parametrize("existing_prefix", [False, True])
 @pytest.mark.parametrize("prefix_selection", [None, "env_var", "prefix", "name"])
-def test_not_env(tmp_home, tmp_root_prefix, prefix_selection, existing_prefix):
+def test_not_env(tmp_home, tmp_root_prefix, prefix_selection, existing_prefix, monkeypatch):
     name = "not_an_env"
     prefix = tmp_root_prefix / "envs" / name
 
@@ -52,10 +52,9 @@ def test_not_env(tmp_home, tmp_root_prefix, prefix_selection, existing_prefix):
     elif prefix_selection == "name":
         infos = helpers.info("-n", name)
     elif prefix_selection == "env_var":
-        os.environ["CONDA_PREFIX"] = str(prefix)
+        monkeypatch.setenv("CONDA_PREFIX", str(prefix))
         infos = helpers.info()
     else:
-        os.environ.pop("CONDA_PREFIX", "")
         infos = helpers.info()
 
     if prefix_selection is None:
@@ -131,11 +130,7 @@ def flags_test(tmp_root_prefix, infos, base_flag, envs_flag, json_flag):
 @pytest.mark.parametrize("envs_flag", ["", "-e", "--envs"])
 @pytest.mark.parametrize("json_flag", ["", "--json"])
 @pytest.mark.parametrize("prefix_selection", [None, "prefix", "name"])
-def test_base_flags(
-    tmp_home, tmp_root_prefix, prefix_selection, base_flag, envs_flag, json_flag, monkeypatch
-):
-    monkeypatch.setenv("CONDA_PREFIX", str(tmp_root_prefix))
-
+def test_base_flags(tmp_home, tmp_root_prefix, prefix_selection, base_flag, envs_flag, json_flag):
     if prefix_selection == "prefix":
         infos = helpers.info("-p", tmp_root_prefix, base_flag, envs_flag, json_flag)
     elif prefix_selection == "name":
diff --git a/micromamba/tests/test_menuinst.py b/micromamba/tests/test_menuinst.py
index 2691d09e3c..dbecf32893 100644
--- a/micromamba/tests/test_menuinst.py
+++ b/micromamba/tests/test_menuinst.py
@@ -59,9 +59,9 @@ def test_simple_shortcut(self):
         not sys.platform.startswith("win"),
         reason="skipping windows-only tests",
     )
-    def test_shortcut_weird_env(self):
+    def test_shortcut_weird_env(self, monkeypatch):
         # note Umlauts do not work yet
-        os.environ["MAMBA_ROOT_PREFIX"] = str(Path("./compl i c ted").absolute())
+        monkeypatch.setenv("MAMBA_ROOT_PREFIX", str(Path("./compl i c ted").absolute()))
         root_prefix = os.environ["MAMBA_ROOT_PREFIX"]
 
         env_name = random_string()
@@ -97,7 +97,6 @@ def test_shortcut_weird_env(self):
         assert not os.path.exists(lnk)
 
         shutil.rmtree(root_prefix)
-        os.environ["MAMBA_ROOT_PREFIX"] = self.root_prefix
 
     # Testing a package (spyder) using menuinst v2 schema
     @pytest.mark.skipif(
diff --git a/micromamba/tests/test_pkg_cache.py b/micromamba/tests/test_pkg_cache.py
index 2c4721e6f4..8d0df5758e 100644
--- a/micromamba/tests/test_pkg_cache.py
+++ b/micromamba/tests/test_pkg_cache.py
@@ -274,12 +274,18 @@ def same_repodata_json_solv(cache: Path):
 class TestMultiplePkgCaches:
     @pytest.mark.parametrize("which_cache", ["tmp_cache", "tmp_cache_alt"])
     def test_different_caches(
-        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, which_cache
+        self,
+        tmp_home,
+        tmp_root_prefix,
+        tmp_cache,
+        tmp_cache_alt,
+        which_cache,
+        monkeypatch,
     ):
         # Test parametrization
         cache = {"tmp_cache": tmp_cache, "tmp_cache_alt": tmp_cache_alt}[which_cache]
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{cache}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{cache}")
         env_name = "some_env"
         res = helpers.create(
             "-n", env_name, package_to_check_requirements(), "-v", "--json", no_dry_run=True
@@ -307,8 +313,9 @@ def test_first_writable(
         tmp_cache_writable,
         tmp_cache,
         tmp_cache_alt,
+        monkeypatch,
     ):
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
 
         env_name = "some_env"
         res = helpers.create(
@@ -333,15 +340,17 @@ def test_first_writable(
         assert linked_file.stat().st_dev == cache_file.stat().st_dev
         assert linked_file.stat().st_ino == cache_file.stat().st_ino
 
-    def test_no_writable(self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt):
+    def test_no_writable(self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, monkeypatch):
         helpers.rmtree(tmp_cache / find_pkg_build(tmp_cache, package_to_check))
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
 
         helpers.create("-n", "myenv", package_to_check_requirements(), "--json", no_dry_run=True)
 
-    def test_no_writable_extracted_dir_corrupted(self, tmp_home, tmp_root_prefix, tmp_cache):
+    def test_no_writable_extracted_dir_corrupted(
+        self, tmp_home, tmp_root_prefix, tmp_cache, monkeypatch
+    ):
         old_cache_dir = tmp_cache / find_pkg_build(tmp_cache, package_to_check)
         if old_cache_dir.is_dir():
             files = glob.glob(
@@ -351,7 +360,7 @@ def test_no_writable_extracted_dir_corrupted(self, tmp_home, tmp_root_prefix, tm
                 file.unlink()
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache}")
 
         with pytest.raises(subprocess.CalledProcessError):
             helpers.create(
@@ -359,7 +368,7 @@ def test_no_writable_extracted_dir_corrupted(self, tmp_home, tmp_root_prefix, tm
             )
 
     def test_first_writable_extracted_dir_corrupted(
-        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt
+        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, monkeypatch
     ):
         test_pkg_bld = find_pkg_build(tmp_cache, package_to_check)
         helpers.rmtree(tmp_cache)  # convenience for cache teardown
@@ -373,7 +382,7 @@ def test_first_writable_extracted_dir_corrupted(
             for file in files:
                 helpers.rmtree(file)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
         env_name = "myenv"
 
         helpers.create(
@@ -414,13 +423,14 @@ def test_extracted_tarball_only_in_non_writable_cache(
         tmp_cache,
         tmp_cache_alt,
         tmp_cache_test_package_dir,
+        monkeypatch,
     ):
         test_pkg_bld = find_pkg_build(tmp_cache, package_to_check)
         helpers.rmtree(find_cache_archive(tmp_cache, test_pkg_bld))
         helpers.rmtree(tmp_cache_alt)
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
         env_name = "myenv"
 
         helpers.create("-n", env_name, package_to_check_requirements(), "--json", no_dry_run=True)
@@ -453,14 +463,14 @@ def test_extracted_tarball_only_in_non_writable_cache(
         assert linked_file.stat().st_ino == non_writable_cache_file.stat().st_ino
 
     def test_missing_extracted_dir_in_non_writable_cache(
-        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt
+        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, monkeypatch
     ):
         test_pkg_bld = find_pkg_build(tmp_cache, package_to_check)
         helpers.rmtree(tmp_cache / test_pkg_bld)
         helpers.rmtree(tmp_cache_alt)
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
         env_name = "myenv"
 
         helpers.create("-n", env_name, package_to_check_requirements(), "--json", no_dry_run=True)
@@ -493,7 +503,7 @@ def test_missing_extracted_dir_in_non_writable_cache(
         assert linked_file.stat().st_ino == writable_cache_file.stat().st_ino
 
     def test_corrupted_extracted_dir_in_non_writable_cache(
-        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt
+        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, monkeypatch
     ):
         test_pkg_bld = find_pkg_build(tmp_cache, package_to_check)
         tmp_cache_test_pkg_dir = Path(tmp_cache / test_pkg_bld)
@@ -506,7 +516,7 @@ def test_corrupted_extracted_dir_in_non_writable_cache(
         os.makedirs(tmp_cache_alt)
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
         env_name = "myenv"
 
         helpers.create(
@@ -545,12 +555,12 @@ def test_corrupted_extracted_dir_in_non_writable_cache(
         assert linked_file.stat().st_ino == writable_cache_file.stat().st_ino
 
     def test_expired_but_valid_repodata_in_non_writable_cache(
-        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt
+        self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt, monkeypatch
     ):
         helpers.rmtree(tmp_cache_alt)
         helpers.recursive_chmod(tmp_cache, 0o500)
 
-        os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache},{tmp_cache_alt}"
+        monkeypatch.setenv("CONDA_PKGS_DIRS", f"{tmp_cache},{tmp_cache_alt}")
         env_name = "myenv"
         test_pkg_bld = find_pkg_build(tmp_cache, package_to_check)
 
diff --git a/micromamba/tests/test_remove.py b/micromamba/tests/test_remove.py
index d184837046..8f31cc11cf 100644
--- a/micromamba/tests/test_remove.py
+++ b/micromamba/tests/test_remove.py
@@ -235,13 +235,15 @@ def test_remove_config_target_prefix(
     cli_env_name,
     env_var,
     current_target_prefix_fallback,
+    monkeypatch,
 ):
     (tmp_root_prefix / "conda-meta").mkdir(parents=True, exist_ok=True)
 
     cmd = []
 
     if use_root_prefix in (None, "cli"):
-        os.environ["MAMBA_DEFAULT_ROOT_PREFIX"] = os.environ.pop("MAMBA_ROOT_PREFIX")
+        monkeypatch.setenv("MAMBA_DEFAULT_ROOT_PREFIX", os.environ["MAMBA_ROOT_PREFIX"])
+        monkeypatch.delenv("MAMBA_ROOT_PREFIX")
 
     if use_root_prefix == "cli":
         cmd += ["-r", str(tmp_root_prefix)]
@@ -262,12 +264,12 @@ def test_remove_config_target_prefix(
         cmd += ["-n", n]
 
     if env_var:
-        os.environ["MAMBA_TARGET_PREFIX"] = p
+        monkeypatch.setenv("MAMBA_TARGET_PREFIX", p)
 
     if not current_target_prefix_fallback:
-        os.environ.pop("CONDA_PREFIX")
+        monkeypatch.delenv("CONDA_PREFIX")
     else:
-        os.environ["CONDA_PREFIX"] = p
+        monkeypatch.setenv("CONDA_PREFIX", p)
 
     if (cli_prefix and cli_env_name) or not (
         cli_prefix or cli_env_name or env_var or current_target_prefix_fallback
diff --git a/micromamba/tests/test_run.py b/micromamba/tests/test_run.py
index 1f2d892a06..ba999788dd 100644
--- a/micromamba/tests/test_run.py
+++ b/micromamba/tests/test_run.py
@@ -28,9 +28,6 @@ def simple_short_program():
 
 
 class TestRun:
-    current_root_prefix = os.environ["MAMBA_ROOT_PREFIX"]
-    current_prefix = os.environ["CONDA_PREFIX"]
-
     @pytest.mark.parametrize("option_flag", common_simple_flags)
     @pytest.mark.parametrize("make_label_flags", next_label_flags)
     def test_fail_without_command(self, option_flag, make_label_flags):
@@ -100,22 +97,17 @@ def test_run_non_existing_cwd(self):
 
 
 @pytest.fixture()
-def temp_env_prefix():
-    previous_root_prefix = os.environ["MAMBA_ROOT_PREFIX"]
-    previous_prefix = os.environ["CONDA_PREFIX"]
-
+def temp_env_prefix(monkeypatch):
     env_name = random_string()
     root_prefix = os.path.expanduser(os.path.join("~", "tmproot" + random_string()))
     prefix = os.path.join(root_prefix, "envs", env_name)
 
-    os.environ["MAMBA_ROOT_PREFIX"] = root_prefix
+    monkeypatch.setenv("MAMBA_ROOT_PREFIX", root_prefix)
     create("-p", prefix, "python")
 
     yield prefix
 
     shutil.rmtree(prefix)
-    os.environ["MAMBA_ROOT_PREFIX"] = previous_root_prefix
-    os.environ["CONDA_PREFIX"] = previous_prefix
 
 
 class TestRunVenv:
diff --git a/micromamba/tests/test_update.py b/micromamba/tests/test_update.py
index 5d9577f156..732a831420 100644
--- a/micromamba/tests/test_update.py
+++ b/micromamba/tests/test_update.py
@@ -25,15 +25,13 @@ class TestUpdate:
     medium_old_version = "0.22"
 
     @staticmethod
-    @pytest.fixture(scope="class")
-    def root(existing_cache):
-        os.environ["MAMBA_ROOT_PREFIX"] = TestUpdate.root_prefix
-        os.environ["CONDA_PREFIX"] = TestUpdate.prefix
+    @pytest.fixture
+    def root(existing_cache, monkeypatch):
+        monkeypatch.setenv("MAMBA_ROOT_PREFIX", TestUpdate.root_prefix)
+        monkeypatch.setenv("CONDA_PREFIX", TestUpdate.prefix)
 
         yield
 
-        os.environ["MAMBA_ROOT_PREFIX"] = TestUpdate.current_root_prefix
-        os.environ["CONDA_PREFIX"] = TestUpdate.current_prefix
         shutil.rmtree(TestUpdate.root_prefix)
 
     @staticmethod
@@ -239,31 +237,26 @@ class TestUpdateConfig:
     prefix = os.path.join(root_prefix, "envs", env_name)
 
     @staticmethod
-    @pytest.fixture(scope="class")
-    def root(existing_cache):
-        os.environ["MAMBA_ROOT_PREFIX"] = TestUpdateConfig.root_prefix
-        os.environ["CONDA_PREFIX"] = TestUpdateConfig.prefix
+    @pytest.fixture
+    def root(existing_cache, monkeypatch):
+        monkeypatch.setenv("MAMBA_ROOT_PREFIX", TestUpdateConfig.root_prefix)
+        monkeypatch.setenv("CONDA_PREFIX", TestUpdateConfig.prefix)
+
         helpers.create("-n", "base", no_dry_run=True)
         helpers.create("-n", TestUpdateConfig.env_name, "--offline", no_dry_run=True)
 
         yield
 
-        os.environ["MAMBA_ROOT_PREFIX"] = TestUpdateConfig.current_root_prefix
-        os.environ["CONDA_PREFIX"] = TestUpdateConfig.current_prefix
         shutil.rmtree(TestUpdateConfig.root_prefix)
 
     @staticmethod
     @pytest.fixture
-    def env_created(root):
-        os.environ["MAMBA_ROOT_PREFIX"] = TestUpdateConfig.root_prefix
-        os.environ["CONDA_PREFIX"] = TestUpdateConfig.prefix
+    def env_created(root, monkeypatch):
+        monkeypatch.setenv("MAMBA_ROOT_PREFIX", TestUpdateConfig.root_prefix)
+        monkeypatch.setenv("CONDA_PREFIX", TestUpdateConfig.prefix)
 
         yield
 
-        for v in ("CONDA_CHANNELS", "MAMBA_TARGET_PREFIX"):
-            if v in os.environ:
-                os.environ.pop(v)
-
     @classmethod
     def config_tests(cls, res, root_prefix=root_prefix, target_prefix=prefix):
         assert res["root_prefix"] == root_prefix
@@ -346,11 +339,13 @@ def test_target_prefix(
         env_var,
         current_target_prefix_fallback,
         env_created,
+        monkeypatch,
     ):
         cmd = []
 
         if root_prefix in (None, "cli"):
-            os.environ["MAMBA_DEFAULT_ROOT_PREFIX"] = os.environ.pop("MAMBA_ROOT_PREFIX")
+            monkeypatch.setenv("MAMBA_DEFAULT_ROOT_PREFIX", os.environ["MAMBA_ROOT_PREFIX"])
+            monkeypatch.delenv("MAMBA_ROOT_PREFIX")
 
         if root_prefix == "cli":
             cmd += ["-r", TestUpdateConfig.root_prefix]
@@ -393,13 +388,13 @@ def test_target_prefix(
             cmd += ["-f", spec_file]
 
         if env_var:
-            os.environ["MAMBA_TARGET_PREFIX"] = p
+            monkeypatch.setenv("MAMBA_TARGET_PREFIX", p)
 
         if not current_target_prefix_fallback:
-            os.environ.pop("CONDA_PREFIX")
-            os.environ.pop("CONDA_DEFAULT_ENV")
+            monkeypatch.delenv("CONDA_PREFIX")
+            monkeypatch.delenv("CONDA_DEFAULT_ENV")
         else:
-            os.environ["CONDA_PREFIX"] = p
+            monkeypatch.setenv("CONDA_PREFIX", p)
 
         if (cli_prefix and cli_env_name) or (yaml_name == "prefix"):
             with pytest.raises(helpers.subprocess.CalledProcessError):
@@ -417,21 +412,22 @@ def test_target_prefix(
     def test_target_prefix_with_no_settings(
         self,
         existing_cache,
+        monkeypatch,
     ):
         # Specify no arg
         cmd = []
 
         # Get the actual set MAMBA_ROOT_PREFIX when setting up `TestUpdateConfig` class
-        os.environ["MAMBA_DEFAULT_ROOT_PREFIX"] = os.environ.pop("MAMBA_ROOT_PREFIX")
-        os.environ.pop("CONDA_PREFIX")
-        os.environ.pop("CONDA_DEFAULT_ENV")
+        monkeypatch.setenv("MAMBA_DEFAULT_ROOT_PREFIX", os.environ["MAMBA_ROOT_PREFIX"])
+        for env_var in ("MAMBA_ROOT_PREFIX", "CONDA_PREFIX", "CONDA_DEFAULT_ENV"):
+            monkeypatch.delenv(env_var)
 
         # Fallback on root prefix
         res = helpers.install(*cmd, "--print-config-only")
         TestUpdateConfig.config_tests(
             res,
-            root_prefix=TestUpdateConfig.root_prefix,
-            target_prefix=TestUpdateConfig.root_prefix,
+            root_prefix=TestUpdateConfig.current_root_prefix,
+            target_prefix=TestUpdateConfig.current_root_prefix,
         )
 
     @pytest.mark.skipif(
@@ -441,13 +437,13 @@ def test_target_prefix_with_no_settings(
     def test_target_prefix_with_no_settings_and_no_env_var(
         self,
         existing_cache,
+        monkeypatch,
     ):
         # Specify no arg
         cmd = []
 
-        os.environ.pop("MAMBA_ROOT_PREFIX")
-        os.environ.pop("CONDA_PREFIX")
-        os.environ.pop("CONDA_DEFAULT_ENV")
+        for env_var in ("MAMBA_ROOT_PREFIX", "CONDA_PREFIX", "CONDA_DEFAULT_ENV"):
+            monkeypatch.delenv(env_var)
 
         # Fallback on root prefix
         res = helpers.install(*cmd, "--print-config-only")
@@ -462,7 +458,7 @@ def test_target_prefix_with_no_settings_and_no_env_var(
     @pytest.mark.parametrize("yaml", (False, True))
     @pytest.mark.parametrize("env_var", (False, True))
     @pytest.mark.parametrize("rc_file", (False, True))
-    def test_channels(self, cli, yaml, env_var, rc_file, env_created):
+    def test_channels(self, cli, yaml, env_var, rc_file, env_created, monkeypatch):
         cmd = []
         expected_channels = []
 
@@ -485,7 +481,7 @@ def test_channels(self, cli, yaml, env_var, rc_file, env_created):
             expected_channels += ["yaml"]
 
         if env_var:
-            os.environ["CONDA_CHANNELS"] = "env_var"
+            monkeypatch.setenv("CONDA_CHANNELS", "env_var")
             expected_channels += ["env_var"]
 
         if rc_file: