diff --git a/exercises/practice/bottle-song/BottleSong.cs b/exercises/practice/bottle-song/BottleSong.cs
index 68dd489b6..2e50b3c76 100644
--- a/exercises/practice/bottle-song/BottleSong.cs
+++ b/exercises/practice/bottle-song/BottleSong.cs
@@ -1,7 +1,9 @@
+using System.Collections.Generic;
+
 public static class BottleSong
 {
-    public static string Recite(int startBottles, int takeDown)
+    public static IEnumerable<string> Recite(int startBottles, int takeDown)
     {
         throw new NotImplementedException("You need to implement this method.");
     }
-}
\ No newline at end of file
+}