separated mutable and immutable maps

1 files changed, 1 insertions, 1 deletions

diff --git a/src/library/scala/collection/mutable/StringBuilder.scala b/src/library/scala/collection/mutable/StringBuilder.scala
index da3ebfcc13..bcb85fe97f 100644
--- a/src/library/scala/collection/mutable/StringBuilder.scala
+++ b/src/library/scala/collection/mutable/StringBuilder.scala
@@ -226,7 +226,7 @@ final class StringBuilder(initCapacity: Int, private val initValue: String)
 
   /* Appends the string representation of the <code>Any</code> argument.
    */
-  def +=(x: Char) { append(x) }
+  def +=(x: Char): this.type = { append(x); this }
 
   def +(x: Char): this.type = { +=(x); this }