diff --git a/src/kit/taosdemo/taosdemo.c b/src/kit/taosdemo/taosdemo.c
index d76185ca43c233c9ac0d4b6e46dc34f74a267670..df1c7bee269a0e663e7a07ebb417f4a1d254859d 100644
--- a/src/kit/taosdemo/taosdemo.c
+++ b/src/kit/taosdemo/taosdemo.c
@@ -4455,7 +4455,7 @@ static int generateDataTail(char *tableName, int32_t tableSeq,
         break;
       }
 
-      buffer += sprintf(buffer, " %s", data);
+      buffer += snprintf(buffer, retLen + 1, "%s", data);
       k++;
       len += retLen;
       remainderBufLen -= retLen;