diff --git a/library/std/src/env.rs b/library/std/src/env.rs
index c665dfd3624..adbd6889624 100644
--- a/library/std/src/env.rs
+++ b/library/std/src/env.rs
@@ -568,7 +568,7 @@ pub struct JoinPathsError {
 ///         let mut paths = env::split_paths(&path).collect::<Vec<_>>();
 ///         paths.push(PathBuf::from("/home/xyz/bin"));
 ///         let new_path = env::join_paths(paths)?;
-///         env::set_var("PATH", &new_path);
+///         unsafe { env::set_var("PATH", &new_path); }
 ///     }
 ///
 ///     Ok(())
diff --git a/library/std/src/process/tests.rs b/library/std/src/process/tests.rs
index 69273d863eb..5879914ca20 100644
--- a/library/std/src/process/tests.rs
+++ b/library/std/src/process/tests.rs
@@ -323,9 +323,13 @@ fn test_capture_env_at_spawn() {
 
     // This variable will not be present if the environment has already
     // been captured above.
-    env::set_var("RUN_TEST_NEW_ENV2", "456");
+    unsafe {
+        env::set_var("RUN_TEST_NEW_ENV2", "456");
+    }
     let result = cmd.output().unwrap();
-    env::remove_var("RUN_TEST_NEW_ENV2");
+    unsafe {
+        env::remove_var("RUN_TEST_NEW_ENV2");
+    }
 
     let output = String::from_utf8_lossy(&result.stdout).to_string();
 
diff --git a/library/std/src/sys/pal/uefi/process.rs b/library/std/src/sys/pal/uefi/process.rs
index 0757f1cb490..9efe9a314f2 100644
--- a/library/std/src/sys/pal/uefi/process.rs
+++ b/library/std/src/sys/pal/uefi/process.rs
@@ -154,8 +154,8 @@ impl Command {
         if let Some(e) = &env {
             for (k, (_, v)) in e {
                 match v {
-                    Some(v) => crate::env::set_var(k, v),
-                    None => crate::env::remove_var(k),
+                    Some(v) => unsafe { crate::env::set_var(k, v) },
+                    None => unsafe { crate::env::remove_var(k) },
                 }
             }
         }
@@ -166,8 +166,8 @@ impl Command {
         if let Some(e) = env {
             for (k, (v, _)) in e {
                 match v {
-                    Some(v) => crate::env::set_var(k, v),
-                    None => crate::env::remove_var(k),
+                    Some(v) => unsafe { crate::env::set_var(k, v) },
+                    None => unsafe { crate::env::remove_var(k) },
                 }
             }
         }
diff --git a/library/std/src/sys/pal/windows/process/tests.rs b/library/std/src/sys/pal/windows/process/tests.rs
index 90f1157d7c4..1377e12162f 100644
--- a/library/std/src/sys/pal/windows/process/tests.rs
+++ b/library/std/src/sys/pal/windows/process/tests.rs
@@ -138,8 +138,10 @@ fn windows_env_unicode_case() {
         let mut cmd = Command::new("cmd");
         cmd.env(a, "1");
         cmd.env(b, "2");
-        env::set_var(a, "1");
-        env::set_var(b, "2");
+        unsafe {
+            env::set_var(a, "1");
+            env::set_var(b, "2");
+        }
 
         for (key, value) in cmd.get_envs() {
             assert_eq!(
diff --git a/library/std/tests/env_modify.rs b/library/std/tests/env_modify.rs
index af151d08851..ba84978b35f 100644
--- a/library/std/tests/env_modify.rs
+++ b/library/std/tests/env_modify.rs
@@ -26,26 +26,32 @@ fn eq(a: Option<OsString>, b: Option<&str>) {
 #[test]
 fn test_set_var() {
     let n = make_rand_name();
-    set_var(&n, "VALUE");
+    unsafe {
+        set_var(&n, "VALUE");
+    }
     eq(var_os(&n), Some("VALUE"));
 }
 
 #[test]
 fn test_remove_var() {
     let n = make_rand_name();
-    set_var(&n, "VALUE");
-    remove_var(&n);
+    unsafe {
+        set_var(&n, "VALUE");
+        remove_var(&n);
+    }
     eq(var_os(&n), None);
 }
 
 #[test]
 fn test_set_var_overwrite() {
     let n = make_rand_name();
-    set_var(&n, "1");
-    set_var(&n, "2");
-    eq(var_os(&n), Some("2"));
-    set_var(&n, "");
-    eq(var_os(&n), Some(""));
+    unsafe {
+        set_var(&n, "1");
+        set_var(&n, "2");
+        eq(var_os(&n), Some("2"));
+        set_var(&n, "");
+        eq(var_os(&n), Some(""));
+    }
 }
 
 #[test]
@@ -58,7 +64,9 @@ fn test_var_big() {
         i += 1;
     }
     let n = make_rand_name();
-    set_var(&n, &s);
+    unsafe {
+        set_var(&n, &s);
+    }
     eq(var_os(&n), Some(&s));
 }
 
@@ -67,10 +75,12 @@ fn test_var_big() {
 fn test_env_set_get_huge() {
     let n = make_rand_name();
     let s = "x".repeat(10000);
-    set_var(&n, &s);
-    eq(var_os(&n), Some(&s));
-    remove_var(&n);
-    eq(var_os(&n), None);
+    unsafe {
+        set_var(&n, &s);
+        eq(var_os(&n), Some(&s));
+        remove_var(&n);
+        eq(var_os(&n), None);
+    }
 }
 
 #[test]
@@ -78,7 +88,9 @@ fn test_env_set_var() {
     let n = make_rand_name();
 
     let mut e = vars_os();
-    set_var(&n, "VALUE");
+    unsafe {
+        set_var(&n, "VALUE");
+    }
     assert!(!e.any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));
 
     assert!(vars_os().any(|(k, v)| { &*k == &*n && &*v == "VALUE" }));
@@ -102,10 +114,12 @@ fn env_home_dir() {
         if #[cfg(unix)] {
             let oldhome = var_to_os_string(var("HOME"));
 
-            set_var("HOME", "/home/MountainView");
-            assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
+            unsafe {
+                set_var("HOME", "/home/MountainView");
+                assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
 
-            remove_var("HOME");
+                remove_var("HOME");
+            }
             if cfg!(target_os = "android") {
                 assert!(home_dir().is_none());
             } else {
@@ -115,33 +129,35 @@ fn env_home_dir() {
                 assert_ne!(home_dir(), Some(PathBuf::from("/home/MountainView")));
             }
 
-            if let Some(oldhome) = oldhome { set_var("HOME", oldhome); }
+            if let Some(oldhome) = oldhome { unsafe { set_var("HOME", oldhome); } }
         } else if #[cfg(windows)] {
             let oldhome = var_to_os_string(var("HOME"));
             let olduserprofile = var_to_os_string(var("USERPROFILE"));
 
-            remove_var("HOME");
-            remove_var("USERPROFILE");
+            unsafe {
+                remove_var("HOME");
+                remove_var("USERPROFILE");
 
-            assert!(home_dir().is_some());
+                assert!(home_dir().is_some());
 
-            set_var("HOME", "/home/PaloAlto");
-            assert_ne!(home_dir(), Some(PathBuf::from("/home/PaloAlto")), "HOME must not be used");
+                set_var("HOME", "/home/PaloAlto");
+                assert_ne!(home_dir(), Some(PathBuf::from("/home/PaloAlto")), "HOME must not be used");
 
-            set_var("USERPROFILE", "/home/MountainView");
-            assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
+                set_var("USERPROFILE", "/home/MountainView");
+                assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
 
-            remove_var("HOME");
+                remove_var("HOME");
 
-            assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
+                assert_eq!(home_dir(), Some(PathBuf::from("/home/MountainView")));
 
-            set_var("USERPROFILE", "");
-            assert_ne!(home_dir(), Some(PathBuf::from("")), "Empty USERPROFILE must be ignored");
+                set_var("USERPROFILE", "");
+                assert_ne!(home_dir(), Some(PathBuf::from("")), "Empty USERPROFILE must be ignored");
 
-            remove_var("USERPROFILE");
+                remove_var("USERPROFILE");
 
-            if let Some(oldhome) = oldhome { set_var("HOME", oldhome); }
-            if let Some(olduserprofile) = olduserprofile { set_var("USERPROFILE", olduserprofile); }
+                if let Some(oldhome) = oldhome { set_var("HOME", oldhome); }
+                if let Some(olduserprofile) = olduserprofile { set_var("USERPROFILE", olduserprofile); }
+            }
         }
     }
 }
@@ -157,7 +173,9 @@ fn test_env_get_set_multithreaded() {
 
     let setter = thread::spawn(|| {
         for _ in 0..100 {
-            set_var("foo", "bar");
+            unsafe {
+                set_var("foo", "bar");
+            }
         }
     });