diff --git a/timely/src/progress/reachability.rs b/timely/src/progress/reachability.rs
index 688e441c2..64d197ab6 100644
--- a/timely/src/progress/reachability.rs
+++ b/timely/src/progress/reachability.rs
@@ -573,22 +573,16 @@ impl<T:Timestamp> Tracker<T> {
             let target_changes =
             self.target_changes
                 .iter()
-                .map(|((target, time), diff)| (target.node, target.port, time.clone(), *diff))
-                .collect::<Vec<_>>();
+                .map(|((target, time), diff)| (target.node, target.port, time, *diff));
 
-            if !target_changes.is_empty() {
-                logger.log_target_updates(target_changes);
-            }
+            logger.log_target_updates(target_changes);
 
             let source_changes =
             self.source_changes
                 .iter()
-                .map(|((source, time), diff)| (source.node, source.port, time.clone(), *diff))
-                .collect::<Vec<_>>();
+                .map(|((source, time), diff)| (source.node, source.port, time, *diff));
 
-            if !source_changes.is_empty() {
-                logger.log_source_updates(source_changes);
-            }
+            logger.log_source_updates(source_changes);
         }
 
         // Step 1: Drain `self.input_changes` and determine actual frontier changes.
@@ -853,22 +847,34 @@ pub mod logging {
         }
 
         /// Log source update events with additional identifying information.
-        pub fn log_source_updates(&mut self, updates: Vec<(usize, usize, T, i64)>) {
-            self.logger.log({
-                SourceUpdate {
-                    tracker_id: self.identifier,
-                    updates,
-                }
-            })
+        pub fn log_source_updates<'a, I>(&mut self, updates: I)
+        where
+            I: IntoIterator<Item = (usize, usize, &'a T, i64)>
+        {
+            let updates: Vec<_> = updates.into_iter().map(|(a,b,c,d)| (a,b,c.clone(),d)).collect();
+            if !updates.is_empty() {
+                self.logger.log({
+                    SourceUpdate {
+                        tracker_id: self.identifier,
+                        updates
+                    }
+                });
+            }
         }
         /// Log target update events with additional identifying information.
-        pub fn log_target_updates(&mut self, updates: Vec<(usize, usize, T, i64)>) {
-            self.logger.log({
-                TargetUpdate {
-                    tracker_id: self.identifier,
-                    updates,
-                }
-            })
+        pub fn log_target_updates<'a, I>(&mut self, updates: I)
+        where
+            I: IntoIterator<Item = (usize, usize, &'a T, i64)>
+        {
+            let updates: Vec<_> = updates.into_iter().map(|(a,b,c,d)| (a,b,c.clone(),d)).collect();
+            if !updates.is_empty() {
+                self.logger.log({
+                    TargetUpdate {
+                        tracker_id: self.identifier,
+                        updates
+                    }
+                });
+            }
         }
     }
 
@@ -929,12 +935,10 @@ impl<T: Timestamp> Drop for Tracker<T> {
                 .flat_map(|(port, target)| {
                     target.pointstamps
                         .updates()
-                        .map(move |(time, diff)| (index, port, time.clone(), -diff))
-                })
-                .collect::<Vec<_>>();
-            if !target_changes.is_empty() {
-                logger.log_target_updates(target_changes);
-            }
+                        .map(move |(time, diff)| (index, port, time, -diff))
+                });
+
+            logger.log_target_updates(target_changes);
 
             let source_changes = per_operator.sources
                 .iter_mut()
@@ -942,12 +946,10 @@ impl<T: Timestamp> Drop for Tracker<T> {
                 .flat_map(|(port, source)| {
                     source.pointstamps
                         .updates()
-                        .map(move |(time, diff)| (index, port, time.clone(), -diff))
-                })
-                .collect::<Vec<_>>();
-            if !source_changes.is_empty() {
-                logger.log_source_updates(source_changes);
-            }
+                        .map(move |(time, diff)| (index, port, time, -diff))
+                });
+
+            logger.log_source_updates(source_changes);
         }
     }
 }