1 files changed, 3 insertions, 2 deletions
diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
index cbf8cc4931..696bc4ab5c 100644
--- a/src/library/scala/collection/Iterator.scala
+++ b/src/library/scala/collection/Iterator.scala
@@ -1111,9 +1111,10 @@ trait Iterator[+A] extends TraversableOnce[A] {
    *    $willNotTerminateInf
    */
   def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Unit = {
+    require(start >= 0 && start < xs.length, s"start $start out of range ${xs.length}")
     var i = start
-    val end = start + math.min(len, xs.length)
-    while (hasNext && i < end) {
+    val end = start + math.min(len, xs.length - start)
+    while (i < end && hasNext) {
       xs(i) = next()
       i += 1
     }