diff --git a/source/libs/executor/src/timewindowoperator.c b/source/libs/executor/src/timewindowoperator.c
index 6418f5305c..757ab09d1a 100644
--- a/source/libs/executor/src/timewindowoperator.c
+++ b/source/libs/executor/src/timewindowoperator.c
@@ -2154,7 +2154,7 @@ static void doKeepLinearInfo(STimeSliceOperatorInfo* pSliceInfo, const SSDataBlo
 
 static void genInterpolationResult(STimeSliceOperatorInfo* pSliceInfo, SExprSupp* pExprSup, SSDataBlock* pResBlock) {
   int32_t rows = pResBlock->info.rows;
-
+  blockDataEnsureCapacity(pResBlock, rows + 1);
   // todo set the correct primary timestamp column
 
   // output the result