diff --git a/src/util/src/tcompare.c b/src/util/src/tcompare.c
index cd914c3851fa84b5992e1994c0cd9bf46f048d76..2ab5ddbbe0ac1025be72e69fe88050d2aa3f73ad 100644
--- a/src/util/src/tcompare.c
+++ b/src/util/src/tcompare.c
@@ -180,6 +180,12 @@ int32_t compareDoubleValDesc(const void* pLeft, const void* pRight) {
 }
 
 int32_t compareLenPrefixedStr(const void *pLeft, const void *pRight) {
+  bool leftIsNull = isNull(pLeft, TSDB_DATA_TYPE_BINARY);
+  bool rightIsNull = isNull(pRight, TSDB_DATA_TYPE_BINARY);
+  if(leftIsNull && rightIsNull) return 0;
+  else if(leftIsNull) return -1;
+  else if(rightIsNull) return 1;
+
   int32_t len1 = varDataLen(pLeft);
   int32_t len2 = varDataLen(pRight);
 
@@ -200,6 +206,12 @@ int32_t compareLenPrefixedStrDesc(const void* pLeft, const void* pRight) {
 }
 
 int32_t compareLenPrefixedWStr(const void *pLeft, const void *pRight) {
+  bool leftIsNull = isNull(pLeft, TSDB_DATA_TYPE_NCHAR);
+  bool rightIsNull = isNull(pRight, TSDB_DATA_TYPE_NCHAR);
+  if(leftIsNull && rightIsNull) return 0;
+  else if(leftIsNull) return -1;
+  else if(rightIsNull) return 1;
+
   int32_t len1 = varDataLen(pLeft);
   int32_t len2 = varDataLen(pRight);