diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index 23cc7324f0..cd67b89208 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -401,8 +401,8 @@ static int32_t concatCopyHelper(const char *input, char *output, bool hasNchar,
       taosMemoryFree(newBuf);
       return TSDB_CODE_SCALAR_CONVERT_ERROR;
     }
-    (void)memcpy(varDataVal(output) + *dataLen, newBuf, varDataLen(input) * TSDB_NCHAR_SIZE);
-    *dataLen += varDataLen(input) * TSDB_NCHAR_SIZE;
+    (void)memcpy(varDataVal(output) + *dataLen, newBuf, len);
+    *dataLen += len;
     taosMemoryFree(newBuf);
   } else {
     (void)memcpy(varDataVal(output) + *dataLen, varDataVal(input), varDataLen(input));