diff --git a/src/stream.rs b/src/stream.rs
index 7057a93..a3f91c5 100644
--- a/src/stream.rs
+++ b/src/stream.rs
@@ -46,6 +46,33 @@ impl ::std::fmt::Debug for Stream {
 }
 
 impl Stream {
+    // Check if the server has closed a stream by performing a one-byte
+    // non-blocking read. If this returns EOF, the server has closed the
+    // connection: return true. If this returns WouldBlock (aka EAGAIN),
+    // that means the connection is still open: return false. Otherwise
+    // return an error.
+    fn serverclosed_stream(stream: &std::net::TcpStream) -> IoResult<bool> {
+        let mut buf = [0; 1];
+        stream.set_nonblocking(true)?;
+
+        let result = match stream.peek(&mut buf) {
+            Ok(0) => Ok(true),
+            Ok(_) => Ok(false), // TODO: Maybe this should produce an "unexpected response" error
+            Err(e) if e.kind() == ErrorKind::WouldBlock => Ok(false),
+            Err(e) => Err(e),
+        };
+        stream.set_nonblocking(false)?;
+
+        result
+    }
+    // Return true if the server has closed this connection.
+    pub(crate) fn server_closed(&self) -> IoResult<bool> {
+        match self {
+            Stream::Http(tcpstream) => Stream::serverclosed_stream(tcpstream),
+            Stream::Https(rustls_stream) => Stream::serverclosed_stream(&rustls_stream.sock),
+            _ => Ok(false),
+        }
+    }
     pub fn is_poolable(&self) -> bool {
         match self {
             Stream::Http(_) => true,
diff --git a/src/unit.rs b/src/unit.rs
index b461caa..a3b4205 100644
--- a/src/unit.rs
+++ b/src/unit.rs
@@ -274,8 +274,14 @@ fn connect_socket(unit: &Unit, use_pooled: bool) -> Result<(Stream, bool), Error
     if use_pooled {
         let state = &mut unit.agent.lock().unwrap();
         if let Some(agent) = state.as_mut() {
-            if let Some(stream) = agent.pool.try_get_connection(&unit.url) {
-                return Ok((stream, true));
+            // The connection may have been closed by the server
+            // due to idle timeout while it was sitting in the pool.
+            // Loop until we find one that is still good or run out of connections.
+            while let Some(stream) = agent.pool.try_get_connection(&unit.url) {
+                let server_closed = stream.server_closed()?;
+                if !server_closed {
+                    return Ok((stream, true));
+                }
             }
         }
     }