diff --git a/build.rs b/build.rs
index 573fa3b..0af6f66 100644
--- a/build.rs
+++ b/build.rs
@@ -47,8 +47,6 @@ fn main()
 		.write_to_file(out_path.join("lean.rs"))
 		.expect("Couldn't write bindings!");
 
-	// This is the path to the object file.
-	let obj_path = output_path.join("extern.o");
 	// This is the path to the static library file.
 	let lib_path = output_path.join("libextern.a");
 
@@ -57,8 +55,8 @@ fn main()
 		.arg("-O")
 		.arg("-c")
 		.arg("-o")
-		.arg(extern_obj_path)
-		.arg(extern_src_path)
+		.arg(&extern_obj_path)
+		.arg(&extern_src_path)
 		.arg("-include")
 		.arg(&input)
 		.output()
@@ -75,7 +73,7 @@ fn main()
 	let lib_output = std::process::Command::new("ar")
 		.arg("rcs")
 		.arg(output_path.join(&lib_path))
-		.arg(obj_path)
+		.arg(&extern_obj_path)
 		.output()
 		.unwrap();
 	#[cfg(target_os = "windows")]
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 5d56faf..292fe49 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,2 +1,2 @@
 [toolchain]
-channel = "nightly"
+channel = "stable"
diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 0000000..7872e67
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,3 @@
+edition = "2021"
+hard_tabs = true
+tab_spaces = 3