emit structured `tracing` events
diff --git a/src/poll.rs b/src/poll.rs
index e60f1e7..6bbaba4 100644
--- a/src/poll.rs
+++ b/src/poll.rs
@@ -492,9 +492,9 @@
         S: event::Source + ?Sized,
     {
         trace!(
-            "registering event source with poller: token={:?}, interests={:?}",
-            token,
-            interests
+            message = "registering event source with poller",
+            ?token,
+            ?interests
         );
         source.register(self, token, interests)
     }
@@ -558,9 +558,9 @@
         S: event::Source + ?Sized,
     {
         trace!(
-            "reregistering event source with poller: token={:?}, interests={:?}",
-            token,
-            interests
+            message = "reregistering event source with poller",
+            ?token,
+            ?interests
         );
         source.reregister(self, token, interests)
     }
diff --git a/src/sys/unix/epoll.rs b/src/sys/unix/epoll.rs
index 29aa563..089a35e 100644
--- a/src/sys/unix/epoll.rs
+++ b/src/sys/unix/epoll.rs
@@ -111,8 +111,8 @@
 
 impl Drop for Selector {
     fn drop(&mut self) {
-        if let Err(err) = syscall!(close(self.ep)) {
-            error!("error closing epoll: {}", err);
+        if let Err(error) = syscall!(close(self.ep)) {
+            error!(message = "error closing epoll", %error);
         }
     }
 }
diff --git a/src/sys/unix/kqueue.rs b/src/sys/unix/kqueue.rs
index 78d6a22..0e3d694 100644
--- a/src/sys/unix/kqueue.rs
+++ b/src/sys/unix/kqueue.rs
@@ -309,8 +309,8 @@
 
 impl Drop for Selector {
     fn drop(&mut self) {
-        if let Err(err) = syscall!(close(self.kq)) {
-            error!("error closing kqueue: {}", err);
+        if let Err(error) = syscall!(close(self.kq)) {
+            error!(message = "error closing kqueue", %error);
         }
     }
 }