diff --git a/artiq/runtime.rs/liblwip/lib.rs b/artiq/runtime.rs/liblwip/lib.rs
index 7eed9497b..5beda5e92 100644
--- a/artiq/runtime.rs/liblwip/lib.rs
+++ b/artiq/runtime.rs/liblwip/lib.rs
@@ -267,14 +267,14 @@ impl<'payload> Pbuf<'payload> {
         unsafe { (*self.raw).len as usize }
     }
 
-    pub fn as_slice(&self) -> &'payload [u8] {
+    pub fn as_slice(&self) -> &[u8] {
         unsafe {
             core::slice::from_raw_parts((*self.raw).payload as *const u8,
                                         (*self.raw).len as usize)
         }
     }
 
-    pub fn as_mut_slice(&mut self) -> &'payload mut [u8] {
+    pub fn as_mut_slice(&mut self) -> &mut [u8] {
         unsafe {
             core::slice::from_raw_parts_mut((*self.raw).payload as *mut u8,
                                             (*self.raw).len as usize)
diff --git a/artiq/runtime.rs/src/sched.rs b/artiq/runtime.rs/src/sched.rs
index 4e698f94b..570541eca 100644
--- a/artiq/runtime.rs/src/sched.rs
+++ b/artiq/runtime.rs/src/sched.rs
@@ -447,10 +447,10 @@ impl<'a> Read for TcpStream<'a> {
         }
 
         let (pbuf, pos) = self.buffer.take().unwrap();
-        let slice = &pbuf.as_slice()[pos..];
-        let len = ::std::cmp::min(buf.len(), slice.len());
-        buf[..len].copy_from_slice(&slice[..len]);
-        if len < slice.len() {
+        let remaining = pbuf.len() - pos;
+        let len = ::std::cmp::min(buf.len(), remaining);
+        buf[..len].copy_from_slice(&pbuf.as_slice()[pos..pos + len]);
+        if len < remaining {
             self.buffer = Some((pbuf, pos + len))
         }
         Ok(len)