diff --git a/239-sliding-window-maximum.go b/239-sliding-window-maximum.go
index ab29aef..43b65bf 100644
--- a/239-sliding-window-maximum.go
+++ b/239-sliding-window-maximum.go
@@ -39,8 +39,20 @@ func (w *Window) Max(prevMax WindowMaximum) WindowMaximum {
 		return maxBruteForce(w.nums, w.begin, w.end)
 	}
 
-	if (w.nums[w.begin-1] == w.nums[w.begin]) && (w.nums[w.end-1] == w.nums[w.end]) {
-		return prevMax
+	if w.nums[w.begin-1] == w.nums[w.begin] {
+		if w.nums[w.end-1] == w.nums[w.end] {
+			return prevMax
+		} else {
+			if w.nums[w.end] >= prevMax.value {
+				return WindowMaximum{value: w.nums[w.end], valid: true, index: w.end}
+			}
+		}
+	} else {
+		if w.nums[w.end-1] == w.nums[w.end] {
+			if w.nums[w.begin] >= prevMax.value {
+				return WindowMaximum{value: w.nums[w.begin], valid: true, index: w.begin}
+			}
+		}
 	}
 
 	if !w.InWindow(prevMax.index) {