diff --git a/src/query/src/qAggMain.c b/src/query/src/qAggMain.c
index 5d1553895dcbd30ef4eeacf4a16cbc0e1cc57353..0e02b1f5ec12092c248dd7a410979f18ce211766 100644
--- a/src/query/src/qAggMain.c
+++ b/src/query/src/qAggMain.c
@@ -2510,7 +2510,7 @@ static void tdigest_merge(SQLFunctionCtx *pCtx) {
   SAPercentileInfo *pOutput = getAPerctInfo(pCtx);
   TDigest* pTDigest = pOutput->pTDigest;
   if(pTDigest->num_centroids == 0) {
-    memcpy(pTDigest, pInput->pTDigest, TDIGEST_SIZE(COMPRESSION));
+    memcpy(pTDigest, pInput->pTDigest, (size_t)TDIGEST_SIZE(COMPRESSION));
     tdigestAutoFill(pTDigest, COMPRESSION);
   } else {
     tdigestMerge(pOutput->pTDigest, pInput->pTDigest);