diff --git a/tests/journal_tests.rs b/tests/journal_tests.rs
index cabc453..fab5790 100644
--- a/tests/journal_tests.rs
+++ b/tests/journal_tests.rs
@@ -10,13 +10,14 @@ use optimizer::storage::{JournalStorage, Storage};
 use optimizer::{Direction, Study};
 
 fn temp_path() -> std::path::PathBuf {
+    use std::sync::atomic::{AtomicU64, Ordering};
+    static COUNTER: AtomicU64 = AtomicU64::new(0);
+
     let mut path = std::env::temp_dir();
     path.push(format!(
-        "optimizer_journal_test_{}.jsonl",
-        std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH)
-            .unwrap()
-            .as_nanos()
+        "optimizer_journal_test_{}_{}.jsonl",
+        std::process::id(),
+        COUNTER.fetch_add(1, Ordering::Relaxed)
     ));
     path
 }