diff --git a/.travis.yml b/.travis.yml
index 53b265ac..d32179a6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@ rust:
   - stable
   - beta
   - nightly
-script: cargo test --verbose -- --test-threads=1
+script: cargo test --verbose
 matrix:
   allow_failures:
     - rust: nightly
diff --git a/src/run.rs b/src/run.rs
index 613ec2ba..e71b91d3 100644
--- a/src/run.rs
+++ b/src/run.rs
@@ -1,9 +1,8 @@
-use crate::util::clean;
+use crate::util;
 use crate::verify::test;
 use console::{style, Emoji};
 use indicatif::ProgressBar;
 use std::fs;
-use std::process::Command;
 use toml::Value;
 
 pub fn run(matches: clap::ArgMatches) -> Result<(), ()> {
@@ -33,20 +32,18 @@ pub fn compile_and_run(filename: &str) -> Result<(), ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Compiling {}...", filename).as_str());
     progress_bar.enable_steady_tick(100);
-    let compilecmd = Command::new("rustc")
-        .args(&[filename, "-o", "temp", "--color", "always"])
-        .output()
-        .expect("fail");
+
+    let compilecmd = util::compile_cmd(filename);
     progress_bar.set_message(format!("Running {}...", filename).as_str());
     if compilecmd.status.success() {
-        let runcmd = Command::new("./temp").output().expect("fail");
+        let runcmd = util::run_cmd();
         progress_bar.finish_and_clear();
 
         if runcmd.status.success() {
             println!("{}", String::from_utf8_lossy(&runcmd.stdout));
             let formatstr = format!("{} Successfully ran {}", Emoji("✅", "✓"), filename);
             println!("{}", style(formatstr).green());
-            clean();
+            util::clean();
             Ok(())
         } else {
             println!("{}", String::from_utf8_lossy(&runcmd.stdout));
@@ -54,7 +51,7 @@ pub fn compile_and_run(filename: &str) -> Result<(), ()> {
 
             let formatstr = format!("{} Ran {} with errors", Emoji("⚠️ ", "!"), filename);
             println!("{}", style(formatstr).red());
-            clean();
+            util::clean();
             Err(())
         }
     } else {
@@ -66,7 +63,7 @@ pub fn compile_and_run(filename: &str) -> Result<(), ()> {
         );
         println!("{}", style(formatstr).red());
         println!("{}", String::from_utf8_lossy(&compilecmd.stderr));
-        clean();
+        util::clean();
         Err(())
     }
 }
diff --git a/src/util.rs b/src/util.rs
index 4a96ee90..6bac972f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,12 +1,41 @@
 use std::fs::remove_file;
+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_file()])
+        .args(RUSTC_COLOR_ARGS)
+        .output()
+        .expect("failed to compile exercise")
+}
+
+pub fn compile_cmd(filename: &str) -> Output {
+    Command::new("rustc")
+        .args(&[filename, "-o", &temp_file()])
+        .args(RUSTC_COLOR_ARGS)
+        .output()
+        .expect("failed to compile exercise")
+}
+
+pub fn run_cmd() -> Output {
+    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());
 }
diff --git a/src/verify.rs b/src/verify.rs
index 5aa2f5cf..afe0884a 100644
--- a/src/verify.rs
+++ b/src/verify.rs
@@ -1,8 +1,7 @@
-use crate::util::clean;
+use crate::util;
 use console::{style, Emoji};
 use indicatif::ProgressBar;
 use std::fs;
-use std::process::Command;
 use toml::Value;
 
 pub fn verify(start_at: Option<&str>) -> Result<(), ()> {
@@ -34,10 +33,7 @@ fn compile_only(filename: &str) -> Result<(), ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Compiling {}...", filename).as_str());
     progress_bar.enable_steady_tick(100);
-    let compilecmd = Command::new("rustc")
-        .args(&[filename, "-o", "temp", "--color", "always"])
-        .output()
-        .expect("fail");
+    let compilecmd = util::compile_cmd(filename);
     progress_bar.finish_and_clear();
     if compilecmd.status.success() {
         let formatstr = format!(
@@ -46,7 +42,7 @@ fn compile_only(filename: &str) -> Result<(), ()> {
             filename
         );
         println!("{}", style(formatstr).green());
-        clean();
+        util::clean();
         Ok(())
     } else {
         let formatstr = format!(
@@ -56,7 +52,7 @@ fn compile_only(filename: &str) -> Result<(), ()> {
         );
         println!("{}", style(formatstr).red());
         println!("{}", String::from_utf8_lossy(&compilecmd.stderr));
-        clean();
+        util::clean();
         Err(())
     }
 }
@@ -65,19 +61,16 @@ pub fn test(filename: &str) -> Result<(), ()> {
     let progress_bar = ProgressBar::new_spinner();
     progress_bar.set_message(format!("Testing {}...", filename).as_str());
     progress_bar.enable_steady_tick(100);
-    let testcmd = Command::new("rustc")
-        .args(&["--test", filename, "-o", "temp", "--color", "always"])
-        .output()
-        .expect("fail");
+    let testcmd = util::compile_test_cmd(filename);
     if testcmd.status.success() {
         progress_bar.set_message(format!("Running {}...", filename).as_str());
-        let runcmd = Command::new("./temp").output().expect("fail");
+        let runcmd = util::run_cmd();
         progress_bar.finish_and_clear();
 
         if runcmd.status.success() {
             let formatstr = format!("{} Successfully tested {}!", Emoji("✅", "✓"), filename);
             println!("{}", style(formatstr).green());
-            clean();
+            util::clean();
             Ok(())
         } else {
             let formatstr = format!(
@@ -87,7 +80,7 @@ pub fn test(filename: &str) -> Result<(), ()> {
             );
             println!("{}", style(formatstr).red());
             println!("{}", String::from_utf8_lossy(&runcmd.stdout));
-            clean();
+            util::clean();
             Err(())
         }
     } else {
@@ -99,7 +92,7 @@ pub fn test(filename: &str) -> Result<(), ()> {
         );
         println!("{}", style(formatstr).red());
         println!("{}", String::from_utf8_lossy(&testcmd.stderr));
-        clean();
+        util::clean();
         Err(())
     }
 }