diff --git a/tokio-stream/src/stream_ext/take.rs b/tokio-stream/src/stream_ext/take.rs
index c75648f6065..07b5c3d57ba 100644
--- a/tokio-stream/src/stream_ext/take.rs
+++ b/tokio-stream/src/stream_ext/take.rs
@@ -64,11 +64,11 @@ where
 
         let (lower, upper) = self.stream.size_hint();
 
-        let lower = cmp::min(lower, self.remaining as usize);
+        let lower = cmp::min(lower, self.remaining);
 
         let upper = match upper {
-            Some(x) if x < self.remaining as usize => Some(x),
-            _ => Some(self.remaining as usize),
+            Some(x) if x < self.remaining => Some(x),
+            _ => Some(self.remaining),
         };
 
         (lower, upper)
diff --git a/tokio-util/src/compat.rs b/tokio-util/src/compat.rs
index 6a8802d9699..7b9de8db2f9 100644
--- a/tokio-util/src/compat.rs
+++ b/tokio-util/src/compat.rs
@@ -232,7 +232,7 @@ impl<T: tokio::io::AsyncSeek> futures_io::AsyncSeek for Compat<T> {
         }
         let res = ready!(self.as_mut().project().inner.poll_complete(cx));
         *self.as_mut().project().seek_pos = None;
-        Poll::Ready(res.map(|p| p as u64))
+        Poll::Ready(res)
     }
 }
 
@@ -255,7 +255,7 @@ impl<T: futures_io::AsyncSeek> tokio::io::AsyncSeek for Compat<T> {
         };
         let res = ready!(self.as_mut().project().inner.poll_seek(cx, pos));
         *self.as_mut().project().seek_pos = None;
-        Poll::Ready(res.map(|p| p as u64))
+        Poll::Ready(res)
     }
 }
 
diff --git a/tokio/src/time/instant.rs b/tokio/src/time/instant.rs
index f18492930a7..59ae32df983 100644
--- a/tokio/src/time/instant.rs
+++ b/tokio/src/time/instant.rs
@@ -188,7 +188,7 @@ impl ops::Sub<Duration> for Instant {
     type Output = Instant;
 
     fn sub(self, rhs: Duration) -> Instant {
-        Instant::from_std(self.std - rhs)
+        Instant::from_std(self.std.checked_sub(rhs).unwrap())
     }
 }
 
diff --git a/tokio/src/util/slab.rs b/tokio/src/util/slab.rs
index 0e16e40e99a..cc1208ebef4 100644
--- a/tokio/src/util/slab.rs
+++ b/tokio/src/util/slab.rs
@@ -560,7 +560,7 @@ impl<T> Slots<T> {
         assert!(slot >= base, "unexpected pointer");
 
         let idx = (slot - base) / width;
-        assert!(idx < self.slots.len() as usize);
+        assert!(idx < self.slots.len());
 
         idx
     }