diff --git a/common/format.go b/common/format.go
index 6fc21af71..7af41f52d 100644
--- a/common/format.go
+++ b/common/format.go
@@ -27,12 +27,12 @@ import (
 // the unnecessary precision off from the formatted textual representation.
 type PrettyDuration time.Duration
 
-var prettyDurationRe = regexp.MustCompile(`\.[0-9]+`)
+var prettyDurationRe = regexp.MustCompile(`\.[0-9]{4,}`)
 
 // String implements the Stringer interface, allowing pretty printing of duration
 // values rounded to three decimals.
 func (d PrettyDuration) String() string {
-	label := fmt.Sprintf("%v", time.Duration(d))
+	label := time.Duration(d).String()
 	if match := prettyDurationRe.FindString(label); len(match) > 4 {
 		label = strings.Replace(label, match, match[:4], 1)
 	}