diff --git a/src/msg_handler/handler.rs b/src/msg_handler/handler.rs
index 3f7218a..122cb05 100644
--- a/src/msg_handler/handler.rs
+++ b/src/msg_handler/handler.rs
@@ -179,11 +179,8 @@ where
     let headers = response.headers_mut();
     remove_connection_header(headers);
     remove_hop_header(headers);
-    append_header_entry_with_comma(
-      headers,
-      "server",
-      &format!("{}/{}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION")),
-    )?;
+    overwrite_header_entry(headers, "server", env!("CARGO_PKG_NAME"))?;
+
     #[cfg(feature = "h3")]
     {
       if self.globals.http3 {
diff --git a/src/msg_handler/utils_headers.rs b/src/msg_handler/utils_headers.rs
index b51a0a1..0a8b76c 100644
--- a/src/msg_handler/utils_headers.rs
+++ b/src/msg_handler/utils_headers.rs
@@ -16,7 +16,6 @@ pub(super) fn apply_upstream_options_to_header(
   upstream: &Upstream,
 ) -> Result<()> {
   for opt in upstream.opts.iter() {
-    println!("{:?}", opt);
     match opt {
       UpstreamOption::OverrideHost => {
         // overwrite HOST value with upstream hostname (like 192.168.xx.x seen from rpxy)
@@ -75,6 +74,23 @@ pub(super) fn add_header_entry_if_not_exist(
   Ok(())
 }
 
+pub(super) fn overwrite_header_entry(
+  headers: &mut HeaderMap,
+  key: &str,
+  value: &str,
+) -> Result<()> {
+  match headers.entry(HeaderName::from_bytes(key.as_bytes())?) {
+    header::Entry::Vacant(entry) => {
+      entry.insert(value.parse::<HeaderValue>()?);
+    }
+    header::Entry::Occupied(mut entry) => {
+      entry.insert(HeaderValue::from_bytes(value.as_bytes())?);
+    }
+  }
+
+  Ok(())
+}
+
 pub(super) fn add_forwarding_header(
   headers: &mut HeaderMap,
   client_addr: &SocketAddr,
diff --git a/src/msg_handler/utils_request.rs b/src/msg_handler/utils_request.rs
index bb32eba..ed3af21 100644
--- a/src/msg_handler/utils_request.rs
+++ b/src/msg_handler/utils_request.rs
@@ -55,13 +55,11 @@ impl<B> ParseHost for Request<B> {
       || {
         let m = headers_host.unwrap().as_bytes();
         if m.starts_with(&[b'[']) {
-          println!("v6 bracket");
           // v6 address with bracket case. if port is specified, always it is in this case.
           let mut iter = m.split(|ptr| ptr == &b'[' || ptr == &b']');
           iter.next().ok_or_else(|| anyhow!("Invalid Host"))?; // first item is always blank
           iter.next().ok_or_else(|| anyhow!("Invalid Host"))
         } else if m.len() - m.split(|v| v == &b':').fold(0, |acc, s| acc + s.len()) >= 2 {
-          println!("v6 non-bracket");
           // v6 address case, if 2 or more ':' is contained
           Ok(m)
         } else {