diff --git a/src/main.rs b/src/main.rs
index d8f05f3..9f78ee7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,15 +14,19 @@ use utils::*;
 
 #[derive(Debug, Clone)]
 struct Args {
-    pub directory: PathBuf,
+    pub directory: Option<PathBuf>,
 }
 
 type A = Arc<Args>;
 
 
 fn parse_args () -> Args {
-    let directory = std::env::args().position(|e| e == "--directory").unwrap() + 1;
-    let directory = PathBuf::from(std::env::args().nth(directory).unwrap());
+    let directory = std::env::args()
+        .position(|e| e == "--directory")
+        .map(|e| e + 1)
+        .map(|d| std::env::args().nth(d))
+        .flatten()
+        .map(|d| PathBuf::from(d));
 
     Args {
         directory
@@ -68,13 +72,17 @@ async fn process (mut stream: TcpStream, args: A) -> Result<()> {
         // p if let Some(echo) = p.strip_prefix("/echo/") => Response::TextPlain(echo), // a nicer way to do that, not available in stable yet
         p if p.starts_with("/echo/") => Response::TextPlain(p.trim_start_matches("/echo/").to_owned()),
         p if p.starts_with("/files/") => {
-            let path = args.directory.join(p.trim_start_matches("/files/"));
-            let mut buf = vec![];
-            if let Ok(mut f) = File::open(path).await {
-                let _ = f.read_to_end(&mut buf).await;
-                Response::OctetStream(buf)
+            if let Some(path) = &args.directory {
+                let path = path.join(p.trim_start_matches("/files/"));
+                let mut buf = vec![];
+                if let Ok(mut f) = File::open(path).await {
+                    let _ = f.read_to_end(&mut buf).await;
+                    Response::OctetStream(buf)
+                } else {
+                    Response::_404
+                }
             } else {
-                Response::_404
+                Response::_500
             }
         },
         _ => Response::_404,
@@ -113,6 +121,7 @@ impl Headers {
 #[derive(Debug, Clone)]
 enum Response {
     _404,
+    _500,
     Empty,
     TextPlain (String),
     OctetStream (Vec<u8>)
@@ -127,6 +136,7 @@ impl Response {
 
         let code = match self {
             Self::_404 => "404 Not Found",
+            Self::_500 => "500 Internal Server Error",
             _ => "200 OK",
         };