diff --git a/artiq/firmware/runtime/sched.rs b/artiq/firmware/runtime/sched.rs
index a5903c2d1..fc3c7ac04 100644
--- a/artiq/firmware/runtime/sched.rs
+++ b/artiq/firmware/runtime/sched.rs
@@ -250,14 +250,26 @@ impl<'a> Io<'a> {
         })
     }
 
-    pub fn until<F: FnMut() -> bool>(&self, mut f: F) -> Result<(), Error> {
+    pub fn inner_until<F: FnMut() -> bool>(
+        &self,
+        timeout: Option<u64>,
+        mut f: F
+    ) -> Result<(), Error> {
         let f = unsafe { mem::transmute::<&mut dyn FnMut() -> bool, *mut dyn FnMut() -> bool>(&mut f) };
         self.suspend(WaitRequest {
-            timeout: None,
-            event:   Some(f)
+            timeout,
+            event: Some(f),
         })
     }
 
+    pub fn until<F: FnMut() -> bool>(&self, f: F) -> Result<(), Error> {
+        self.inner_until(None, f)
+    }
+
+    pub fn until_with_timeout<F: FnMut() -> bool>(&self, timeout: u64, f: F) -> Result<(), Error> {
+        self.inner_until(Some(timeout), f)
+    }
+
     pub fn until_ok<T, E, F>(&self, mut f: F) -> Result<T, Error>
         where F: FnMut() -> result::Result<T, E>
     {
@@ -313,7 +325,15 @@ macro_rules! until {
             let $var = network.get_socket::<$ty>(handle);
             $cond
         })
-    })
+    });
+    ($socket:expr, $ty:ty, timeout=$timeout:expr, |$var:ident| $cond:expr) => ({
+        let (network, handle) = ($socket.io.network.clone(), $socket.handle);
+        $socket.io.until_with_timeout($timeout, move || {
+            let mut network = network.borrow_mut();
+            let $var = network.get_socket::<$ty>(handle);
+            $cond
+        })
+    });
 }
 
 type TcpSocketBuffer = ::smoltcp::socket::TcpSocketBuffer<'static>;
@@ -567,6 +587,27 @@ impl<'a> Write for TcpStream<'a> {
 impl<'a> Drop for TcpStream<'a> {
     fn drop(&mut self) {
         self.with_lower(|s| s.close());
+        let result = until!(
+            self, TcpSocketLower, timeout=clock::get_ms() + 1000, |s| !s.is_active()
+        );
+        let unsent_bytes = self.with_lower(|s| s.send_queue());
+        match result{
+            Ok(()) => {
+                if unsent_bytes != 0 {
+                    // This is normal if we received a reset whilst sending
+                    debug!("Dropping socket with {} bytes unsent", unsent_bytes)
+                }
+            }
+            Err(Error::TimedOut) => {
+                warn!(
+                    "Timed out whilst waiting for socket to close during drop, with {} unsent bytes",
+                    unsent_bytes
+                );
+            }
+            Err(e) => {
+                error!("Unexpected error whilst waiting for socket to close during drop: {:?}", e)
+            }
+        }
         self.io.network.borrow_mut().remove_socket(self.handle);
     }
 }