diff --git a/src/cargo/core/compiler/job_queue.rs b/src/cargo/core/compiler/job_queue.rs
index fd86611bcc5..55832cb906a 100644
--- a/src/cargo/core/compiler/job_queue.rs
+++ b/src/cargo/core/compiler/job_queue.rs
@@ -95,6 +95,9 @@ pub struct JobQueue<'a, 'cfg> {
 /// It is created from JobQueue when we have fully assembled the crate graph
 /// (i.e., all package dependencies are known).
 struct DrainState<'a, 'cfg> {
+    // This is the length of the DependencyQueue when starting out
+    total_units: usize,
+
     queue: DependencyQueue<Unit<'a>, Artifact, Job>,
     tx: Sender<Message>,
     rx: Receiver<Message>,
@@ -341,6 +344,7 @@ impl<'a, 'cfg> JobQueue<'a, 'cfg> {
         let (tx, rx) = channel();
         let progress = Progress::with_style("Building", ProgressStyle::Ratio, cx.bcx.config);
         let state = DrainState {
+            total_units: self.queue.len(),
             queue: self.queue,
             tx,
             rx,
@@ -713,7 +717,7 @@ impl<'a, 'cfg> DrainState<'a, 'cfg> {
             .collect::<Vec<_>>();
         drop(self.progress.tick_now(
             self.finished,
-            self.queue.len(),
+            self.total_units,
             &format!(": {}", active_names.join(", ")),
         ));
     }
diff --git a/src/cargo/util/progress.rs b/src/cargo/util/progress.rs
index 05715e4fe32..d62600379cb 100644
--- a/src/cargo/util/progress.rs
+++ b/src/cargo/util/progress.rs
@@ -224,6 +224,7 @@ impl<'cfg> State<'cfg> {
 
 impl Format {
     fn progress(&self, cur: usize, max: usize) -> Option<String> {
+        assert!(cur <= max);
         // Render the percentage at the far right and then figure how long the
         // progress bar is
         let pct = (cur as f64) / (max as f64);