diff --git a/magic-nix-cache/src/flakehub.rs b/magic-nix-cache/src/flakehub.rs
index a987f13..a6ec86e 100644
--- a/magic-nix-cache/src/flakehub.rs
+++ b/magic-nix-cache/src/flakehub.rs
@@ -31,7 +31,7 @@ pub async fn init_cache(
     flakehub_api_server: &Url,
     flakehub_api_server_netrc: &Path,
     flakehub_cache_server: &Url,
-    flakehub_flake_name: &str,
+    flakehub_flake_name: Option<String>,
     store: Arc<NixStore>,
 ) -> Result<State> {
     // Parse netrc to get the credentials for api.flakehub.com.
@@ -122,10 +122,18 @@ pub async fn init_cache(
 
     // Get the cache UUID for this project.
     let cache_name = {
-        let url = flakehub_api_server
-            .join(&format!("project/{}", flakehub_flake_name))
+        let mut url = flakehub_api_server
+            .join("project")
             .map_err(|_| Error::Config(format!("bad URL '{}'", flakehub_api_server)))?;
 
+        if let Some(flakehub_flake_name) = flakehub_flake_name {
+            if !flakehub_flake_name.is_empty() {
+                url = flakehub_api_server
+                    .join(&format!("project/{}", flakehub_flake_name))
+                    .map_err(|_| Error::Config(format!("bad URL '{}'", flakehub_api_server)))?;
+            }
+        }
+
         let response = reqwest::Client::new()
             .get(url.to_owned())
             .header("User-Agent", USER_AGENT)
diff --git a/magic-nix-cache/src/main.rs b/magic-nix-cache/src/main.rs
index 9614bdb..9f94e54 100644
--- a/magic-nix-cache/src/main.rs
+++ b/magic-nix-cache/src/main.rs
@@ -166,15 +166,7 @@ async fn main_cli() -> Result<()> {
         let flakehub_api_server_netrc = args
             .flakehub_api_server_netrc
             .ok_or_else(|| anyhow!("--flakehub-api-server-netrc is required"))?;
-        let flakehub_flake_name = args
-            .flakehub_flake_name
-            .ok_or_else(|| {
-                tracing::debug!(
-                    "--flakehub-flake-name was not set, inferring from $GITHUB_REPOSITORY env var"
-                );
-                std::env::var("GITHUB_REPOSITORY")
-            })
-            .map_err(|_| anyhow!("--flakehub-flake-name and $GITHUB_REPOSITORY were both unset"))?;
+        let flakehub_flake_name = args.flakehub_flake_name;
 
         match flakehub::init_cache(
             &args
@@ -182,7 +174,7 @@ async fn main_cli() -> Result<()> {
                 .ok_or_else(|| anyhow!("--flakehub-api-server is required"))?,
             &flakehub_api_server_netrc,
             &flakehub_cache_server,
-            &flakehub_flake_name,
+            flakehub_flake_name,
             store.clone(),
         )
         .await