diff --git a/packer/progressbar_test.go b/packer/progressbar_test.go
new file mode 100644
index 000000000..89cbe862a
--- /dev/null
+++ b/packer/progressbar_test.go
@@ -0,0 +1,58 @@
+package packer
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestStackableProgressBar_race(t *testing.T) {
+	bar := &StackableProgressBar{}
+
+	start42Fn := func() { bar.Start(42) }
+	finishFn := func() { bar.Finish() }
+	add21 := func() { bar.Add(21) }
+	// prefix := func() { bar.prefix() }
+
+	type fields struct {
+		pre   func()
+		calls []func()
+		post  func()
+	}
+	tests := []struct {
+		name       string
+		fields     fields
+		iterations int
+	}{
+		{"all public", fields{nil, []func(){start42Fn, finishFn, add21, add21}, finishFn}, 300},
+		{"all public", fields{start42Fn, []func(){add21, add21}, finishFn}, 300},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			for i := 0; i < tt.iterations; i++ {
+				if tt.fields.pre != nil {
+					tt.fields.pre()
+				}
+				var startWg, endWg sync.WaitGroup
+				startWg.Add(1)
+				endWg.Add(len(tt.fields.calls))
+				for _, call := range tt.fields.calls {
+					call := call
+					go func() {
+						defer endWg.Done()
+						startWg.Wait()
+						call()
+					}()
+				}
+				startWg.Done() // everyone is initialized, let's unlock everyone at the same time.
+				// ....
+				endWg.Wait() // wait for all calls to return.
+				if tt.fields.post != nil {
+					tt.fields.post()
+				}
+			}
+		})
+	}
+
+}