diff --git a/crates/uv/tests/it/common/mod.rs b/crates/uv/tests/it/common/mod.rs
index 01b805e5b..b26f07c40 100644
--- a/crates/uv/tests/it/common/mod.rs
+++ b/crates/uv/tests/it/common/mod.rs
@@ -755,7 +755,7 @@ impl TestContext {
             "Activate with: source $1/[BIN]/activate".to_string(),
         ));
         filters.push((
-            r"Activate with: source (.*)/bin/activate(?:\.\w+)?".to_string(),
+            r"Activate with: source (.*)/bin/activate".to_string(),
             "Activate with: source $1/[BIN]/activate".to_string(),
         ));
 
@@ -927,11 +927,6 @@ impl TestContext {
         if activate_venv {
             command.env(EnvVars::VIRTUAL_ENV, self.venv.as_os_str());
         }
-
-        if cfg!(unix) {
-            // Avoid locale issues in tests
-            command.env(EnvVars::LC_ALL, "C");
-        }
     }
 
     /// Create a `pip compile` command for testing.
@@ -1271,6 +1266,9 @@ impl TestContext {
         command
     }
 
+    /// The path to the Python interpreter in the venv.
+    ///
+    /// Don't use this for `Command::new`, use `Self::python_command` instead.
     pub fn interpreter(&self) -> PathBuf {
         let venv = &self.venv;
         if cfg!(unix) {
@@ -1544,8 +1542,50 @@ impl TestContext {
 
     /// Creates a new `Command` that is intended to be suitable for use in
     /// all tests, but with the given binary.
+    ///
+    /// The command contains only essential env vars to avoid the tests getting
+    /// influenced by host `UV_*`, XDG, or other environment variables.
     fn new_command_with(bin: &Path) -> Command {
-        Command::new(bin)
+        let mut command = Command::new(bin);
+
+        // Only forward essential environment variables, to avoid influencing behavior and snapshots
+        // from the host env.
+        command.env_clear();
+        if cfg!(unix) {
+            // For Unix, we pretend the tests run in a bash for the activate hint, for Windows, shell
+            // detection assumes PowerShell if `PROMPT` is not set.
+            command.env("SHELL", "/bin/bash");
+
+            // Avoid locale issues in tests
+            command.env(EnvVars::LC_ALL, "C");
+
+            // STOPSHIP(konsti): This is for pyodide on my machine
+            for env_var in ["VOLTA_HOME"] {
+                if let Some(value) = env::var_os(env_var) {
+                    command.env(env_var, value);
+                }
+            }
+        } else if cfg!(windows) {
+            let env_vars = &[
+                "PATH",
+                "PATHEXT",
+                "ProgramFiles",
+                "ProgramFiles(x86)",
+                "RANDOM",
+                // https://github.com/rust-lang/rust/issues/114737
+                "SYSTEMROOT",
+                "SystemDrive",
+            ];
+            for env_var in env_vars {
+                if let Some(system_root) = env::var_os(env_var) {
+                    command.env(env_var, system_root);
+                }
+            }
+        } else {
+            unimplemented!("Only Unix and Windows are supported");
+        }
+
+        command
     }
 }
 
@@ -1608,7 +1648,7 @@ pub fn get_python(version: &PythonVersion) -> PathBuf {
 
 /// Create a virtual environment at the given path.
 pub fn create_venv_from_executable<P: AsRef<Path>>(path: P, cache_dir: &ChildPath, python: &Path) {
-    assert_cmd::Command::new(get_bin())
+    TestContext::new_command_with(&get_bin())
         .arg("venv")
         .arg(path.as_ref().as_os_str())
         .arg("--clear")
diff --git a/crates/uv/tests/it/pip_install.rs b/crates/uv/tests/it/pip_install.rs
index 1255a77a1..f83a4c6d6 100644
--- a/crates/uv/tests/it/pip_install.rs
+++ b/crates/uv/tests/it/pip_install.rs
@@ -5872,6 +5872,8 @@ fn deptry_gitignore() {
     uv_snapshot!(context.filters(), context.pip_install()
         .arg(format!("deptry_reproducer @ {}", source_dist_dir.join("deptry_reproducer-0.1.0.tar.gz").simplified_display()))
         .arg("--strict")
+        // Set by the test harness, needed by the test
+        .env("RUSTUP_TOOLCHAIN", std::env::var("RUSTUP_TOOLCHAIN").unwrap())
         .current_dir(source_dist_dir), @r###"
     success: true
     exit_code: 0