Fix for #3204. No review.

2 files changed, 3 insertions, 1 deletions

diff --git a/src/library/scala/collection/SortedMap.scala b/src/library/scala/collection/SortedMap.scala
index 48c3dcd725..7b0d35220e 100644
--- a/src/library/scala/collection/SortedMap.scala
+++ b/src/library/scala/collection/SortedMap.scala
@@ -21,7 +21,7 @@ import mutable.Builder
  */
 trait SortedMap[A, +B] extends Map[A, B] with SortedMapLike[A, B, SortedMap[A, B]] {
   /** Needs to be overridden in subclasses. */
-  override def empty = SortedMap.empty[A, B]
+  override def empty: SortedMap[A, B] = SortedMap.empty[A, B]
 
   override protected[this] def newBuilder: Builder[(A, B), SortedMap[A, B]] =
     immutable.SortedMap.newBuilder[A, B]
diff --git a/src/library/scala/collection/immutable/SortedMap.scala b/src/library/scala/collection/immutable/SortedMap.scala
index 316cab9b50..baf7f5451e 100644
--- a/src/library/scala/collection/immutable/SortedMap.scala
+++ b/src/library/scala/collection/immutable/SortedMap.scala
@@ -31,6 +31,8 @@ trait SortedMap[A, +B] extends Map[A, B]
   override protected[this] def newBuilder : Builder[(A, B), SortedMap[A, B]] =
     SortedMap.newBuilder[A, B]
 
+  override def empty: SortedMap[A, B] = SortedMap.empty
+
   override def updated [B1 >: B](key: A, value: B1): SortedMap[A, B1] = this + ((key, value))
 
   /** Add a key/value pair to this map.