diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce83279..0e600dd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changelog
 
 - [Changelog](#changelog)
+  - [6.0.3](#603)
   - [6.0.2](#602)
   - [6.0.1](#601)
   - [6.0.0](#600)
@@ -35,6 +36,13 @@
 
 ---
 
+## 6.0.3
+
+Released on 15/10/2024
+
+- Added `Send` marker to the Closure: `dyn Fn(SocketAddr) -> Pin<Box<dyn Future<Output = FtpResult<TcpStream>> + Send>> + Send;`
+- Added unit test to guarantee that FtpStream stays `Send`
+
 ## 6.0.2
 
 Released on 14/10/2024
diff --git a/Cargo.toml b/Cargo.toml
index 54739b6..b0fd2fa 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@ members = ["suppaftp", "suppaftp-cli"]
 resolver = "2"
 
 [workspace.package]
-version = "6.0.2"
+version = "6.0.3"
 edition = "2021"
 authors = [
   "Christian Visintin <christian.visintin@veeso.dev>",
diff --git a/README.md b/README.md
index ec8b883..940e93b 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@
 </p>
 
 <p align="center">Developed by <a href="https://veeso.github.io/">veeso</a> and <a href="/~https://github.com/mattnenterprise">Matt McCoy</a></p>
-<p align="center">Current version: 6.0.2 (14/10/2024)</p>
+<p align="center">Current version: 6.0.3 (15/10/2024)</p>
 
 <p align="center">
   <a href="https://opensource.org/licenses/MIT"
diff --git a/suppaftp/src/async_ftp/mod.rs b/suppaftp/src/async_ftp/mod.rs
index 4fba65e..9fc4131 100644
--- a/suppaftp/src/async_ftp/mod.rs
+++ b/suppaftp/src/async_ftp/mod.rs
@@ -41,7 +41,7 @@ use crate::types::Features;
 ///
 /// It takes a [`SocketAddr`] and returns a [`TcpStream`].
 pub type PassiveStreamBuilder =
-    dyn Fn(SocketAddr) -> Pin<Box<dyn Future<Output = FtpResult<TcpStream>> + Send>>;
+    dyn Fn(SocketAddr) -> Pin<Box<dyn Future<Output = FtpResult<TcpStream>> + Send>> + Send;
 
 /// Stream to interface with the FTP server. This interface is only for the command stream.
 pub struct ImplAsyncFtpStream<T>
@@ -257,7 +257,9 @@ where
     /// to create the [`TcpStream`] for the data connection in passive mode.
     pub fn passive_stream_builder<F>(mut self, stream_builder: F) -> Self
     where
-        F: Fn(SocketAddr) -> Pin<Box<dyn Future<Output = FtpResult<TcpStream>> + Send>> + 'static,
+        F: Fn(SocketAddr) -> Pin<Box<dyn Future<Output = FtpResult<TcpStream>> + Send>>
+            + Send
+            + 'static,
     {
         self.passive_stream_builder = Box::new(stream_builder);
         self
@@ -1447,6 +1449,27 @@ mod test {
             });
     }
 
+    /// Test if the stream is Send
+    fn is_send<T: Send>(_send: T) {}
+
+    #[async_attributes::test]
+    async fn test_ftp_stream_should_be_send() {
+        crate::log_init();
+        let ftp_stream = AsyncFtpStream::connect("test.rebex.net:21")
+            .await
+            .unwrap()
+            .passive_stream_builder(|addr| {
+                Box::pin(async move {
+                    println!("Connecting to {}", addr);
+                    TcpStream::connect(addr)
+                        .await
+                        .map_err(FtpError::ConnectionError)
+                })
+            });
+
+        is_send::<AsyncFtpStream>(ftp_stream);
+    }
+
     // -- test utils
 
     #[cfg(feature = "with-containers")]
diff --git a/suppaftp/src/sync_ftp/mod.rs b/suppaftp/src/sync_ftp/mod.rs
index e5ba5fb..9824e9e 100644
--- a/suppaftp/src/sync_ftp/mod.rs
+++ b/suppaftp/src/sync_ftp/mod.rs
@@ -1497,4 +1497,20 @@ mod test {
                 TcpStream::connect(addr).map_err(FtpError::ConnectionError)
             });
     }
+
+    /// Test if the stream is Send
+    fn is_send<T: Send>(_send: T) {}
+
+    #[test]
+    fn test_ftp_stream_should_be_send() {
+        crate::log_init();
+        let ftp_stream = FtpStream::connect("test.rebex.net:21")
+            .unwrap()
+            .passive_stream_builder(|addr| {
+                println!("Connecting to {}", addr);
+                TcpStream::connect(addr).map_err(FtpError::ConnectionError)
+            });
+
+        is_send::<FtpStream>(ftp_stream);
+    }
 }