diff --git a/days/src/main/kotlin/Day09.kt b/days/src/main/kotlin/Day09.kt
index d3da114..2061335 100644
--- a/days/src/main/kotlin/Day09.kt
+++ b/days/src/main/kotlin/Day09.kt
@@ -8,11 +8,15 @@ import be.vandewalleh.aoc.utils.input.createDay
 @Day(9)
 class Day09(@Lines val input: Input<LongArray>) {
 
+    private var part1Result = 0L
+
     fun part1() = input.value
         .toList()
+        .asSequence()
         .windowed(size = 26)
         .find { !isValid(it) }
         ?.last()
+        ?.also { part1Result = it }
 
     private fun isValid(items: List<Long>): Boolean {
         val preamble = items.take(25)
@@ -29,15 +33,13 @@ class Day09(@Lines val input: Input<LongArray>) {
     }
 
     fun part2(): Long {
-        val a = 731031916L
         var size = 2
         while (true) {
             for (startIndex in input.value.indices) {
                 val lastIndex = input.value.size - 1 - size
                 if (startIndex + size > lastIndex) break
                 val slice = input.value.sliceArray(startIndex..startIndex + size)
-                val sum = slice.reduce { acc, l -> acc + l }
-                if (sum == a) return slice.minOrNull()!! + slice.maxOrNull()!!
+                if (slice.sum() == part1Result) return slice.minOrNull()!! + slice.maxOrNull()!!
             }
             size++
         }