diff --git a/lib/pure/algorithm.nim b/lib/pure/algorithm.nim
index 7af1b2ad86..89c83a8a43 100644
--- a/lib/pure/algorithm.nim
+++ b/lib/pure/algorithm.nim
@@ -36,10 +36,10 @@ proc reverse*[T](a: var openArray[T]) =
 
 proc reversed*[T](a: openArray[T], first, last: int): seq[T] =
   ## returns the reverse of the array `a[first..last]`.
-  result = newSeq[T](last - first)
+  result = newSeq[T](last - first + 1)
   var x = first
   var y = last
-  while x < last:
+  while x <= last:
     result[x] = a[y]
     dec(y)
     inc(x)