diff --git a/runtime/src/main/kotlin/kotlin/collections/Maps.kt b/runtime/src/main/kotlin/kotlin/collections/Maps.kt
index 98d84e841ac..3950c4353a3 100644
--- a/runtime/src/main/kotlin/kotlin/collections/Maps.kt
+++ b/runtime/src/main/kotlin/kotlin/collections/Maps.kt
@@ -21,4 +21,4 @@ internal inline actual fun <K, V> Map<K, V>.toSingletonMapOrSelf(): Map<K, V> =
 
 // creates a singleton copy of map
 internal actual fun <K, V> Map<out K, V>.toSingletonMap(): Map<K, V>
-        = this.toMutableMap() // TODO
+        = with(entries.iterator().next()) { mutableMapOf(key to value) }