diff --git a/src/ConfigFiles/getDownLoadUrl.php b/src/ConfigFiles/getDownLoadUrl.php
index 7da2ba6a..3be9edda 100644
--- a/src/ConfigFiles/getDownLoadUrl.php
+++ b/src/ConfigFiles/getDownLoadUrl.php
@@ -20,6 +20,7 @@
 $lastestVersionStr = "1.2.3"; // X.Y.Z
 $DLURL = "http://download.my-software.com/my-software/1.2.3/mySoftware.1.2.3.Installer.exe";
 $curentVersion = $_GET["version"];
+$param = $_GET["param"]; // optional
 
 if ($curentVersion >= $lastestVersion)
 {
diff --git a/src/ConfigFiles/gup.xml b/src/ConfigFiles/gup.xml
index 115ce1b7..30158540 100644
--- a/src/ConfigFiles/gup.xml
+++ b/src/ConfigFiles/gup.xml
@@ -20,9 +20,16 @@
 <GUPInput>
 	<!-- optional.
 	It's the current version of your program. WinGup will add "?version=versionNumber" at the end of InfoUrl.
-	This parameter will be ignored if you pass directly your version number to WinGup via command line.
+	This parameter will be ignored if you pass directly your version number to WinGup via command line "-v".
 	-->
 	<Version>4.6</Version>
+	
+	<!-- optional.
+	It could be whatever you want.
+	If this node is present and the VALUE is not empty,	WinGup will add "&param=VALUE" at the end of version param.
+	This parameter will be ignored if you pass directly your param VALUE to WinGup via command line "-p".
+	-->
+	<Param>x64</Param>
 
 	<!-- Mandatory.
 	This is the url (your web application, both http and https are supported) from where your WinGup gets the update information.
diff --git a/src/change.log b/src/change.log
index 3a680434..72917b9a 100644
--- a/src/change.log
+++ b/src/change.log
@@ -1,3 +1,8 @@
+GUP v4.1 new feature:
+
+1. Add option -pVALUE for custom parameter. The VALUE can be retieved from "param" via GET method on the server side. 
+
+
 GUP v4 new feature:
 
-1. 64 bits build.
\ No newline at end of file
+1. 64-bit build.
\ No newline at end of file
diff --git a/src/resource.h b/src/resource.h
index 137ee515..2957fe8f 100644
--- a/src/resource.h
+++ b/src/resource.h
@@ -20,8 +20,8 @@
 #ifndef RESOURCE_H
 #define RESOURCE_H
 
-#define VERSION_VALUE "4.0\0"
-#define VERSION_DIGITALVALUE 4, 0, 0, 0
+#define VERSION_VALUE "4.1\0"
+#define VERSION_DIGITALVALUE 4, 1, 0, 0
 
 #define IDD_PROGRESS_DLG 1001
 #define IDD_PROXY_DLG 1002
diff --git a/src/winmain.cpp b/src/winmain.cpp
index bd24bf71..fbb51502 100644
--- a/src/winmain.cpp
+++ b/src/winmain.cpp
@@ -42,7 +42,7 @@ static string winGupUserAgent = "WinGup/";
 static string dlFileName = "";
 
 const char FLAG_OPTIONS[] = "-options";
-const char FLAG_VERSION[] = "-v";
+//const char FLAG_VERSION[] = "-v";
 const char FLAG_VERBOSE[] = "-verbose";
 const char FLAG_HELP[] = "--help";
 
@@ -55,7 +55,7 @@ const char MSGID_HELP[] = "Usage :\r\
 \r\
 gup --help\r\
 gup -options\r\
-gup [-verbose] [-vVERSION_VALUE]\r\
+gup [-verbose] [-vVERSION_VALUE] [-pCUSTOM_PARAM]\r\
 \r\
     --help : Show this help message (and quit program).\r\
     -options : Show the proxy configuration dialog (and quit program).\r\
@@ -63,6 +63,9 @@ gup [-verbose] [-vVERSION_VALUE]\r\
          VERSION_VALUE is the current version number of program to update.\r\
          If you pass the version number as the argument,\r\
          then the version set in the gup.xml will be overrided.\r\
+	-p : Launch GUP with CUSTOM_PARAM.\r\
+	     CUSTOM_PARAM will pass to destination by using GET method\r\
+         with argument name \"param\"\r\
     -verbose : Show error/warning message if any.";
 
 std::string thirdDoUpdateDlgButtonLabel;
@@ -359,6 +362,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR lpszCmdLine, int)
 	bool isVerbose = false;
 	bool isHelp = false;
 	string version = "";
+	string customParam = "";
 
 	if (lpszCmdLine && lpszCmdLine[0])
 	{
@@ -366,6 +370,7 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR lpszCmdLine, int)
 		isVerbose = isInList(FLAG_VERBOSE, lpszCmdLine);
 		isHelp = isInList(FLAG_HELP, lpszCmdLine);
 		version = getParamVal('v', lpszCmdLine);
+		customParam = getParamVal('p', lpszCmdLine);
 	}
 
 	if (isHelp)
@@ -420,12 +425,27 @@ int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE, LPSTR lpszCmdLine, int)
 		if (curl) 
 		{
 			std::string urlComplete = gupParams.getInfoLocation() + "?version=";
-			if (version != "")
+			if (!version.empty())
 				urlComplete += version;
 			else
 				urlComplete += gupParams.getCurrentVersion();
 
+			if (!customParam.empty())
+			{
+				string customParamPost = "&param=";
+				customParamPost += customParam;
+				urlComplete += customParamPost;
+			}
+			else if (!gupParams.getParam().empty())
+			{
+				string customParamPost = "&param=";
+				customParamPost += gupParams.getParam();
+				urlComplete += customParamPost;
+			}
+
 			curl_easy_setopt(curl, CURLOPT_URL, urlComplete.c_str());
+
+
             curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, TRUE);
 
 			curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, getUpdateInfo);
diff --git a/src/xmlTools.cpp b/src/xmlTools.cpp
index a09524ad..16a2331f 100644
--- a/src/xmlTools.cpp
+++ b/src/xmlTools.cpp
@@ -21,8 +21,7 @@
 
 using namespace std;
 
-GupParameters::GupParameters(const char * xmlFileName) : _currentVersion(""), _className2Close(""), _messageBoxTitle(""),\
-                                                         _3rdButton_wm_cmd(0), _3rdButton_wParam(0), _3rdButton_lParam(0), _isSilentMode(true)
+GupParameters::GupParameters(const char * xmlFileName)
 {
 	_xmlDoc.LoadFile(xmlFileName);
 
@@ -43,6 +42,20 @@ GupParameters::GupParameters(const char * xmlFileName) : _currentVersion(""), _c
 			}
 		}
 	}
+
+	TiXmlNode *paramNode = root->FirstChildElement("Param");
+	if (paramNode)
+	{
+		TiXmlNode *n = paramNode->FirstChild();
+		if (n)
+		{
+			const char *val = n->Value();
+			if (val)
+			{
+				_param = val;
+			}
+		}
+	}
 	
 	TiXmlNode *infoURLNode = root->FirstChildElement("InfoUrl");
 	if (!infoURLNode)
diff --git a/src/xmlTools.h b/src/xmlTools.h
index 9d770f32..76d57542 100644
--- a/src/xmlTools.h
+++ b/src/xmlTools.h
@@ -33,6 +33,7 @@ class GupParameters : public XMLTool {
 	GupParameters(const char * xmlFileName);
 	
 	const std::string & getCurrentVersion() const { return _currentVersion;};
+	const std::string & getParam() const { return _param; };
 	const std::string & getInfoLocation() const {return _infoUrl;};
 	const std::string & getClassName() const {return _className2Close;};
 	const std::string & getMessageBoxTitle() const {return _messageBoxTitle;};
@@ -53,14 +54,15 @@ class GupParameters : public XMLTool {
 
 private:
 	std::string _currentVersion;
+	std::string _param;
 	std::string _infoUrl;
 	std::string _className2Close;
 	std::string _messageBoxTitle;
 	std::string _softwareName;
 	bool _isMessageBoxModal = false;
-	int _3rdButton_wm_cmd;
-	int _3rdButton_wParam;
-	int _3rdButton_lParam;
+	int _3rdButton_wm_cmd = 0;
+	int _3rdButton_wParam = 0;
+	int _3rdButton_lParam = 0;
 	std::string _3rdButton_label;
 	bool _isSilentMode = true;
 };