diff --git a/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt b/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt
index b9fb3a9..fde0f29 100644
--- a/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt
+++ b/nise-backend/src/main/kotlin/com/nisemoe/nise/replays/Wtc.kt
@@ -263,7 +263,7 @@ private fun cumSum(arr: ShortArray): ShortArray {
     val cumArr = ShortArray(arr.size)
 
     cumArr[0] = arr.first()
-    for (index in 1..<arr.size - 1) {
+    for (index in 1..<arr.size) {
         cumArr[index] = (arr[index] + cumArr[index - 1]).toShort()
     }