diff --git a/velox/exec/RowsStreamingWindowBuild.cpp b/velox/exec/RowsStreamingWindowBuild.cpp
index 8c72e0babf93..82b83da325db 100644
--- a/velox/exec/RowsStreamingWindowBuild.cpp
+++ b/velox/exec/RowsStreamingWindowBuild.cpp
@@ -102,6 +102,15 @@ void RowsStreamingWindowBuild::noMoreInput() {
 
 std::shared_ptr<WindowPartition> RowsStreamingWindowBuild::nextPartition() {
   VELOX_CHECK(hasNextPartition());
+
+  if (outputPartition_ > 0) {
+    windowPartitions_.erase(
+        windowPartitions_.begin(), windowPartitions_.begin() + 1);
+    windowPartitions_.shrink_to_fit();
+    --outputPartition_;
+    --inputPartition_;
+  }
+
   return windowPartitions_[++outputPartition_];
 }