diff --git a/Cargo.toml b/Cargo.toml
index 0e6b0c3c0..519351881 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -80,6 +80,7 @@ used_underscore_items = "allow"
 
 [workspace.lints.rust]
 mismatched_lifetime_syntaxes = "allow"
+deprecated_safe_2024 = "deny"
 
 [profile.optimize]
 inherits = "release"
diff --git a/crates/cli/src/highlight.rs b/crates/cli/src/highlight.rs
index a2cb01cf4..0c6bfe2d5 100644
--- a/crates/cli/src/highlight.rs
+++ b/crates/cli/src/highlight.rs
@@ -474,7 +474,7 @@ mod tests {
         assert_eq!(style.css, None);
 
         // darkcyan is an ANSI color and is preserved
-        env::set_var("COLORTERM", "");
+        unsafe { env::set_var("COLORTERM", "") };
         parse_style(&mut style, Value::String(DARK_CYAN.to_string()));
         assert_eq!(
             style.ansi.get_fg_color(),
@@ -483,7 +483,7 @@ mod tests {
         assert_eq!(style.css, Some("color: #00af87".to_string()));
 
         // junglegreen is not an ANSI color and is preserved when the terminal supports it
-        env::set_var("COLORTERM", "truecolor");
+        unsafe { env::set_var("COLORTERM", "truecolor") };
         parse_style(&mut style, Value::String(JUNGLE_GREEN.to_string()));
         assert_eq!(
             style.ansi.get_fg_color(),
@@ -492,7 +492,7 @@ mod tests {
         assert_eq!(style.css, Some("color: #26a69a".to_string()));
 
         // junglegreen gets approximated as cadetblue when the terminal does not support it
-        env::set_var("COLORTERM", "");
+        unsafe { env::set_var("COLORTERM", "") };
         parse_style(&mut style, Value::String(JUNGLE_GREEN.to_string()));
         assert_eq!(
             style.ansi.get_fg_color(),
@@ -501,9 +501,9 @@ mod tests {
         assert_eq!(style.css, Some("color: #26a69a".to_string()));
 
         if let Ok(environment_variable) = original_environment_variable {
-            env::set_var("COLORTERM", environment_variable);
+            unsafe { env::set_var("COLORTERM", environment_variable) };
         } else {
-            env::remove_var("COLORTERM");
+            unsafe { env::remove_var("COLORTERM") };
         }
     }
 }
diff --git a/crates/xtask/src/benchmark.rs b/crates/xtask/src/benchmark.rs
index 2b15db320..5a2b33fc3 100644
--- a/crates/xtask/src/benchmark.rs
+++ b/crates/xtask/src/benchmark.rs
@@ -4,18 +4,20 @@ use crate::{bail_on_err, Benchmark};
 
 pub fn run(args: &Benchmark) -> Result<()> {
     if let Some(ref example) = args.example_file_name {
-        std::env::set_var("TREE_SITTER_BENCHMARK_EXAMPLE_FILTER", example);
+        unsafe { std::env::set_var("TREE_SITTER_BENCHMARK_EXAMPLE_FILTER", example) };
     }
 
     if let Some(ref language) = args.language {
-        std::env::set_var("TREE_SITTER_BENCHMARK_LANGUAGE_FILTER", language);
+        unsafe { std::env::set_var("TREE_SITTER_BENCHMARK_LANGUAGE_FILTER", language) };
     }
 
     if args.repetition_count != 5 {
-        std::env::set_var(
-            "TREE_SITTER_BENCHMARK_REPETITION_COUNT",
-            args.repetition_count.to_string(),
-        );
+        unsafe {
+            std::env::set_var(
+                "TREE_SITTER_BENCHMARK_REPETITION_COUNT",
+                args.repetition_count.to_string(),
+            );
+        };
     }
 
     if args.debug {
diff --git a/crates/xtask/src/test.rs b/crates/xtask/src/test.rs
index 6b8d82438..15054de1b 100644
--- a/crates/xtask/src/test.rs
+++ b/crates/xtask/src/test.rs
@@ -11,7 +11,7 @@ use crate::{bail_on_err, Test};
 
 pub fn run(args: &Test) -> Result<()> {
     let test_flags = if args.address_sanitizer {
-        env::set_var("CFLAGS", "-fsanitize=undefined,address");
+        unsafe { env::set_var("CFLAGS", "-fsanitize=undefined,address") };
 
         // When the Tree-sitter C library is compiled with the address sanitizer, the address
         // sanitizer runtime library needs to be linked into the final test executable. When
@@ -21,12 +21,14 @@ pub fn run(args: &Test) -> Result<()> {
         bail_on_err(&output, "Failed to get clang runtime dir")?;
         let runtime_dir = String::from_utf8(output.stdout)?;
         if runtime_dir.contains("/Xcode.app/") {
-            env::set_var(
-                "RUSTFLAGS",
-                format!(
-                    "-C link-arg=-L{runtime_dir} -C link-arg=-lclang_rt.asan_osx_dynamic -C link-arg=-Wl,-rpath,{runtime_dir}"
-                ),
-            );
+            unsafe {
+                env::set_var(
+                    "RUSTFLAGS",
+                    format!(
+                        "-C link-arg=-L{runtime_dir} -C link-arg=-lclang_rt.asan_osx_dynamic -C link-arg=-Wl,-rpath,{runtime_dir}"
+                    ),
+                );
+            };
         }
 
         // Specify a `--target` explicitly. This is required for address sanitizer support.
@@ -46,22 +48,34 @@ pub fn run(args: &Test) -> Result<()> {
         String::new()
     };
     if let Some(language) = &args.language {
-        env::set_var("TREE_SITTER_LANGUAGE", language);
+        unsafe {
+            env::set_var("TREE_SITTER_LANGUAGE", language);
+        }
     }
     if let Some(example) = &args.example {
-        env::set_var("TREE_SITTER_EXAMPLE_INCLUDE", example);
+        unsafe {
+            env::set_var("TREE_SITTER_EXAMPLE_INCLUDE", example);
+        }
     }
     if let Some(seed) = args.seed {
-        env::set_var("TREE_SITTER_SEED", seed.to_string());
+        unsafe {
+            env::set_var("TREE_SITTER_SEED", seed.to_string());
+        }
     }
     if let Some(iterations) = args.iterations {
-        env::set_var("TREE_SITTER_ITERATIONS", iterations.to_string());
+        unsafe {
+            env::set_var("TREE_SITTER_ITERATIONS", iterations.to_string());
+        }
     }
     if args.debug {
-        env::set_var("TREE_SITTER_LOG", "1");
+        unsafe {
+            env::set_var("TREE_SITTER_LOG", "1");
+        }
     }
     if args.debug_graph {
-        env::set_var("TREE_SITTER_LOG_GRAPHS", "1");
+        unsafe {
+            env::set_var("TREE_SITTER_LOG_GRAPHS", "1");
+        }
     }
 
     if args.g {