diff --git a/nix-actions-cache/src/api.rs b/nix-actions-cache/src/api.rs
index 66a888f..8e2297f 100644
--- a/nix-actions-cache/src/api.rs
+++ b/nix-actions-cache/src/api.rs
@@ -2,7 +2,9 @@
 //!
 //! This API is intended to be used by nix-installer-action.
 
-use axum::{extract::Extension, routing::post, Json, Router};
+use std::net::SocketAddr;
+
+use axum::{extract::Extension, routing::post, http::uri::Uri, Json, Router};
 use axum_macros::debug_handler;
 use serde::Serialize;
 
@@ -55,7 +57,8 @@ async fn workflow_finish(
         .collect::<Vec<_>>();
 
     tracing::info!("Pushing {} new paths", new_paths.len());
-    upload_paths(new_paths.clone()).await?;
+    let store_uri = make_store_uri(&state.self_endpoint);
+    upload_paths(new_paths.clone(), &store_uri).await?;
 
     let sender = state.shutdown_sender.lock().await.take().unwrap();
     sender.send(()).unwrap();
@@ -66,3 +69,13 @@ async fn workflow_finish(
         num_new_paths: new_paths.len(),
     }))
 }
+
+fn make_store_uri(self_endpoint: &SocketAddr) -> String {
+    Uri::builder()
+        .scheme("http")
+        .authority(self_endpoint.to_string())
+        .path_and_query("/?compression=zstd&parallel-compression=true")
+        .build()
+        .unwrap()
+        .to_string()
+}
diff --git a/nix-actions-cache/src/main.rs b/nix-actions-cache/src/main.rs
index 1e1346c..7105dd5 100644
--- a/nix-actions-cache/src/main.rs
+++ b/nix-actions-cache/src/main.rs
@@ -92,6 +92,11 @@ struct StateInner {
 
     /// Set of store path hashes that are not present in GHAC.
     narinfo_nagative_cache: RwLock<HashSet<String>>,
+
+    /// Endpoint of ourselves.
+    ///
+    /// This is used by our Action API to invoke `nix copy` to upload new paths.
+    self_endpoint: SocketAddr,
 }
 
 fn main() {
@@ -124,6 +129,7 @@ fn main() {
         shutdown_sender: Mutex::new(Some(shutdown_sender)),
         original_paths: Mutex::new(HashSet::new()),
         narinfo_nagative_cache: RwLock::new(HashSet::new()),
+        self_endpoint: args.listen.to_owned(),
     });
 
     let app = Router::new()
diff --git a/nix-actions-cache/src/util.rs b/nix-actions-cache/src/util.rs
index c5faeab..40c3b5b 100644
--- a/nix-actions-cache/src/util.rs
+++ b/nix-actions-cache/src/util.rs
@@ -38,16 +38,15 @@ pub async fn get_store_paths() -> Result<HashSet<PathBuf>> {
     Ok(paths)
 }
 
-/// Uploads a list of store paths to the cache.
-pub async fn upload_paths(mut paths: Vec<PathBuf>) -> Result<()> {
+/// Uploads a list of store paths to a store URI.
+pub async fn upload_paths(mut paths: Vec<PathBuf>, store_uri: &str) -> Result<()> {
     // When the daemon started Nix may not have been installed
     let env_path = Command::new("sh")
         .args(&["-lc", "echo $PATH"])
         .output()
         .await?
         .stdout;
-    let env_path = String::from_utf8(env_path)
-        .expect("PATH contains invalid UTF-8");
+    let env_path = String::from_utf8(env_path).expect("PATH contains invalid UTF-8");
 
     while !paths.is_empty() {
         let mut batch = Vec::new();
@@ -63,8 +62,7 @@ pub async fn upload_paths(mut paths: Vec<PathBuf>) -> Result<()> {
 
         let status = Command::new("nix")
             .args(&["--extra-experimental-features", "nix-command"])
-            // FIXME: Port and compression settings
-            .args(&["copy", "--to", "http://127.0.0.1:3000"])
+            .args(&["copy", "--to", store_uri])
             .args(&batch)
             .env("PATH", &env_path)
             .status()