diff --git a/src/util.rs b/src/util.rs
index 8fcf693f..6bac972f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,11 +1,15 @@
 use std::fs::remove_file;
-use std::process::{Command, Output};
+use std::process::{self, Command, Output};
 
 const RUSTC_COLOR_ARGS: &[&str] = &["--color", "always"];
 
+fn temp_file() -> String {
+    format!("./temp_{}", process::id())
+}
+
 pub fn compile_test_cmd(filename: &str) -> Output {
     Command::new("rustc")
-        .args(&["--test", filename, "-o", "temp"])
+        .args(&["--test", filename, "-o", &temp_file()])
         .args(RUSTC_COLOR_ARGS)
         .output()
         .expect("failed to compile exercise")
@@ -13,25 +17,25 @@ pub fn compile_test_cmd(filename: &str) -> Output {
 
 pub fn compile_cmd(filename: &str) -> Output {
     Command::new("rustc")
-        .args(&[filename, "-o", "temp"])
+        .args(&[filename, "-o", &temp_file()])
         .args(RUSTC_COLOR_ARGS)
         .output()
         .expect("failed to compile exercise")
 }
 
 pub fn run_cmd() -> Output {
-    Command::new("./temp")
+    Command::new(&temp_file())
         .output()
         .expect("failed to run exercise")
 }
 
 pub fn clean() {
-    let _ignored = remove_file("temp");
+    let _ignored = remove_file(&temp_file());
 }
 
 #[test]
 fn test_clean() {
-    std::fs::File::create("temp").unwrap();
+    std::fs::File::create(&temp_file()).unwrap();
     clean();
-    assert!(!std::path::Path::new("temp").exists());
+    assert!(!std::path::Path::new(&temp_file()).exists());
 }