diff --git a/README.md b/README.md
index efe88c4..582f140 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ openssl req -x509 -newkey rsa:4096 -keyout key.rsa -out cert.pem \
 agate 0.0.0.0:1965 path/to/content/ cert.pem key.rsa
 ```
 
-When a client requests the URL `gemini://example.com/foo/bar`, Agate will respond with the file at `path/to/content/foo/bar`.  If there is a directory at that path, Agate will look for a file named `index.gemini` inside that directory.
+When a client requests the URL `gemini://example.com/foo/bar`, Agate will respond with the file at `path/to/content/foo/bar`.  If there is a directory at that path, Agate will look for a file named `index.gmi` inside that directory.
 
 [Gemini]: https://gemini.circumlunar.space/
 [Rust]: https://www.rust-lang.org/
diff --git a/src/main.rs b/src/main.rs
index 4bc9c96..324ab84 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -125,14 +125,14 @@ async fn send_response<W: Write + Unpin>(url: &Url, mut stream: W) -> Result {
     }
     if path.is_dir().await {
         if url.as_str().ends_with('/') {
-            path.push("index.gemini");
+            path.push("index.gmi");
         } else {
             return redirect_slash(url, stream).await;
         }
     }
     match async_std::fs::read(&path).await {
         Ok(body) => {
-            if path.extension() == Some(OsStr::new("gemini")) {
+            if path.extension() == Some(OsStr::new("gmi")) {
                 stream.write_all(b"20 text/gemini\r\n").await?;
             } else {
                 let mime = tree_magic::from_u8(&body);