--- /src/OptionHandlerFactory.cc	2018-05-15 20:33:25.000000000 +0800
+++ /src/OptionHandlerFactory.cc	2018-07-05 10:40:25.000000000 +0800
@@ -440,7 +440,7 @@
   {
     OptionHandler* op(new NumberOptionHandler(PREF_MAX_CONNECTION_PER_SERVER,
                                               TEXT_MAX_CONNECTION_PER_SERVER,
-                                              "1", 1, 16, 'x'));
+                                              "64", 1, -1, 'x'));
     op->addTag(TAG_BASIC);
     op->addTag(TAG_FTP);
     op->addTag(TAG_HTTP);
@@ -501,7 +501,7 @@
   }
   {
     OptionHandler* op(new UnitNumberOptionHandler(
-        PREF_MIN_SPLIT_SIZE, TEXT_MIN_SPLIT_SIZE, "20M", 1_m, 1_g, 'k'));
+        PREF_MIN_SPLIT_SIZE, TEXT_MIN_SPLIT_SIZE, "1M", 1_k, 1_g, 'k'));
     op->addTag(TAG_BASIC);
     op->addTag(TAG_FTP);
     op->addTag(TAG_HTTP);
@@ -905,7 +905,7 @@ std::vector<OptionHandler*> OptionHandlerFactory::createOptionHandlers()
   }
   {
     OptionHandler* op(new UnitNumberOptionHandler(
-        PREF_PIECE_LENGTH, TEXT_PIECE_LENGTH, "1M", 1_m, 1_g));
+        PREF_PIECE_LENGTH, TEXT_PIECE_LENGTH, "1M", 1_k, 1_g));
     op->addTag(TAG_ADVANCED);
     op->addTag(TAG_FTP);
     op->addTag(TAG_HTTP);