diff --git a/libraries/stdlib/src/kotlin/time/DurationUnit.kt b/libraries/stdlib/src/kotlin/time/DurationUnit.kt
index c5bd804c356..8699e12e282 100644
--- a/libraries/stdlib/src/kotlin/time/DurationUnit.kt
+++ b/libraries/stdlib/src/kotlin/time/DurationUnit.kt
@@ -63,4 +63,5 @@ internal fun DurationUnit.shortName(): String = when (this) {
     DurationUnit.MINUTES -> "m"
     DurationUnit.HOURS -> "h"
     DurationUnit.DAYS -> "d"
-}
\ No newline at end of file
+    else -> error("Unknown unit: $this")
+}