diff --git a/src/ProcessUtils.cpp b/src/ProcessUtils.cpp
index 2e4cf75..75b0c09 100644
--- a/src/ProcessUtils.cpp
+++ b/src/ProcessUtils.cpp
@@ -268,28 +268,37 @@ int ProcessUtils::runElevatedMac(const std::string& executable,
 }
 #endif
 
-#ifdef PLATFORM_WINDOWS
-int ProcessUtils::runElevatedWindows(const std::string& executable,
-							const std::list<std::string>& arguments)
+// convert a list of arguments in a space-separated string.
+// Arguments containing spaces are enclosed in quotes
+std::string quoteArgs(const std::list<std::string>& arguments)
 {
-	std::string args;
-
-	// quote process arguments
+	std::string quotedArgs;
 	for (std::list<std::string>::const_iterator iter = arguments.begin();
 	     iter != arguments.end();
 	     iter++)
 	{
 		std::string arg = *iter;
 
-		if (!arg.empty() && arg.at(0) != '"' && arg.at(arg.size()-1) != '"')
-        {
+		bool isQuoted = !arg.empty() &&
+		                 arg.at(0) == '"' &&
+		                 arg.at(arg.size()-1) == '"';
+
+		if (!isQuoted && arg.find(' ') != std::string::npos)
+		{
 			arg.insert(0,"\"");
 			arg.append("\"");
-        }
+		}
+		quotedArgs += arg;
+		quotedArgs += " ";
+	}
+	return quotedArgs;
+}
 
-		args += arg;
-		args += " ";
-    }
+#ifdef PLATFORM_WINDOWS
+int ProcessUtils::runElevatedWindows(const std::string& executable,
+							const std::list<std::string>& arguments)
+{
+	std::string args = quoteArgs(arguments);
 
 	SHELLEXECUTEINFO executeInfo;
 	ZeroMemory(&executeInfo,sizeof(executeInfo));
@@ -350,18 +359,12 @@ PLATFORM_PID ProcessUtils::runAsyncUnix(const std::string& executable,
 
 #ifdef PLATFORM_WINDOWS
 int ProcessUtils::runWindows(const std::string& executable,
-                             const std::list<std::string>& args,
+                             const std::list<std::string>& _args,
                              RunMode runMode)
 {
-	std::string commandLine = executable;
-	for (std::list<std::string>::const_iterator iter = args.begin(); iter != args.end(); iter++)
-	{
-		if (!commandLine.empty())
-		{
-			commandLine.append(" ");
-		}
-		commandLine.append(*iter);
-	}
+	std::list<std::string> args(_args);
+	args.push_front(executable);
+	std::string commandLine = quoteArgs(args);
 
 	STARTUPINFO startupInfo;
 	ZeroMemory(&startupInfo,sizeof(startupInfo));
diff --git a/src/tests/test-update.rb b/src/tests/test-update.rb
index 962cdb2..db8b7d4 100755
--- a/src/tests/test-update.rb
+++ b/src/tests/test-update.rb
@@ -3,7 +3,10 @@
 require 'fileutils.rb'
 require 'rbconfig'
 
-INSTALL_DIR = File.expand_path("install-dir/")
+# Install directory - this contains a space to check
+# for correct escaping of paths when passing comamnd
+# line arguments under Windows
+INSTALL_DIR = File.expand_path("install dir/")
 PACKAGE_DIR = File.expand_path("package-dir/")
 
 if (RbConfig::CONFIG['host_os'] =~ /mswin|mingw/)
@@ -86,8 +89,11 @@ FileUtils.cp("../#{UPDATER_NAME}","#{PACKAGE_DIR}/#{UPDATER_NAME}")
 # make sure that it looks in the correct directory for
 # the file_list.xml file and packages
 #
+install_path = File.absolute_path(INSTALL_DIR)
 Dir.chdir(INSTALL_DIR) do
-	system("#{PACKAGE_DIR}/#{UPDATER_NAME} --install-dir #{INSTALL_DIR} --package-dir #{PACKAGE_DIR} --script file_list.xml")
+	cmd = "#{PACKAGE_DIR}/#{UPDATER_NAME} --install-dir \"#{install_path}\" --package-dir \"#{PACKAGE_DIR}\" --script file_list.xml"
+	puts "Running '#{cmd}'"
+	system(cmd)
 end
 
 # TODO - Correctly wait until updater has finished