diff --git a/asconfig/utils.go b/asconfig/utils.go
index 3fc2e18..47ed576 100644
--- a/asconfig/utils.go
+++ b/asconfig/utils.go
@@ -741,7 +741,7 @@ func isSizeOrTime(key string) (bool, humanize) {
 	switch key {
 	case "default-ttl", "max-ttl", "tomb-raider-eligible-age",
 		"tomb-raider-period", "nsup-period", "migrate-fill-delay",
-		"tls-refresh-period", "ship-versions-interval":
+		"tls-refresh-period", "ship-versions-interval", "mrt-duration":
 		return true, deHumanizeTime
 
 	case "memory-size", "filesize", "write-block-size",