diff --git a/src/util/src/tcompare.c b/src/util/src/tcompare.c
index 1043ee4c37..ee367b459c 100644
--- a/src/util/src/tcompare.c
+++ b/src/util/src/tcompare.c
@@ -156,14 +156,16 @@ int32_t compareLenPrefixedWStr(const void *pLeft, const void *pRight) {
   if (len1 != len2) {
     return len1 > len2? 1:-1;
   } else {
-    char pLeftTerm[len1 + 1];
-    char pRightTerm[len2 + 1];
-    memset(pLeftTerm, 0, len1 + 1);
-    memset(pRightTerm, 0, len2 + 1);
+    char *pLeftTerm = (char *)tcalloc(len1 + 1, sizeof(char));
+    char *pRightTerm = (char *)tcalloc(len1 + 1, sizeof(char));
     memcpy(pLeftTerm, varDataVal(pLeft), len1);
     memcpy(pRightTerm, varDataVal(pRight), len2);
 
     int32_t ret = wcsncmp((void *)pLeftTerm, (void *)pRightTerm, len1/TSDB_NCHAR_SIZE);
+
+    tfree(pLeftTerm);
+    tfree(pRightTerm);
+
     if (ret == 0) {
       return 0;
     } else {