diff --git a/crates/applications/buffer_proto5/src/main.rs b/crates/applications/buffer_proto5/src/main.rs
index c3894ac..15da818 100644
--- a/crates/applications/buffer_proto5/src/main.rs
+++ b/crates/applications/buffer_proto5/src/main.rs
@@ -335,6 +335,12 @@ fn derive_geometries(p: GeomParams) -> Option<Geometries> {
     })
 }
 
+fn ensure_out_dir(id: u32) -> String {
+    let base = format!("out/applications/buffer_proto5/{}", id);
+    let _ = std::fs::create_dir_all(&base);
+    base
+}
+
 fn run_sim(id: u32, p: Params, g: Geometries) -> Results {
     info!("run_sim {}: {:?}", id, p);
 
@@ -346,10 +352,11 @@ fn run_sim(id: u32, p: Params, g: Geometries) -> Results {
     info!("ferro1: {:?}", g.ferro1_region.center());
     info!("ferro2: {:?}", g.ferro2_region.center());
 
-    let base = format!("buffer5-{}", id);
-    let prefix = format!("out/{}/{}-{}-{}setmA-{}setps-{}clkmA-{}clkps-{}um-{}ferromaj-{}:{}wraps-{}:{}cov-{:?}clk",
-        base,
+    let base = ensure_out_dir(id);
+    let prefix = format!(
+        "{}/{}-{}-{}setmA-{}setps-{}clkmA-{}clkps-{}um-{}ferromaj-{}:{}wraps-{}:{}cov-{:?}clk",
         base,
+        id,
         *g.dim.to_index(p.geom.feat_size),
         (p.peak_set_current * 1e3).round() as i64,
         (p.set_duration * 1e12).round() as i64,
@@ -630,7 +637,7 @@ fn main() {
     );
 
     let mut geom_cache = DiskCache::new_with_supplier(
-        &format!("out/buffer5-{}/.geom_cache", i),
+        &format!("{}/.geom_cache", ensure_out_dir(i)),
         |geom: &GeomParams| derive_geometries(geom.clone())
     );