diff --git a/framework/platform-dx/game.cpp b/framework/platform-dx/game.cpp
index 4fae11f..d3ab2ce 100644
--- a/framework/platform-dx/game.cpp
+++ b/framework/platform-dx/game.cpp
@@ -34,7 +34,7 @@ namespace xna {
 	int Game::StartGameLoop() {
 		MSG msg{};		
 
-		impl->_stepTimer = DX::StepTimer();
+		impl->_stepTimer = xna::StepTimer();
 
 		do {
 			if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
diff --git a/inc/platform-dx/implementations.hpp b/inc/platform-dx/implementations.hpp
index d57f41e..a33e718 100644
--- a/inc/platform-dx/implementations.hpp
+++ b/inc/platform-dx/implementations.hpp
@@ -468,7 +468,7 @@ namespace xna {
 	private:
 		friend class Game;
 		
-		DX::StepTimer _stepTimer{};
+		xna::StepTimer _stepTimer{};
 	};
 
 	struct SoundEffectInstance::PlatformImplementation {
diff --git a/inc/platform-dx/steptimer.hpp b/inc/platform-dx/steptimer.hpp
index 2986e79..5f63b4c 100644
--- a/inc/platform-dx/steptimer.hpp
+++ b/inc/platform-dx/steptimer.hpp
@@ -1,3 +1,5 @@
+#ifndef XNA_PLATFORM_DX_SLEPTIME_HPP
+#define XNA_PLATFORM_DX_SLEPTIME_HPP
 //
 // StepTimer.h - A simple timer that provides elapsed time information
 //
@@ -10,7 +12,7 @@
 #include <exception>
 
 
-namespace DX
+namespace xna
 {
     // Helper class for animation and simulation timing.
     class StepTimer
@@ -189,3 +191,5 @@ namespace DX
         uint64_t m_targetElapsedTicks;
     };
 }
+
+#endif
diff --git a/samples/CMakeLists.txt b/samples/CMakeLists.txt
index bbeea5b..24ef843 100644
--- a/samples/CMakeLists.txt
+++ b/samples/CMakeLists.txt
@@ -3,4 +3,5 @@
 #
 
 # Add source to this project's executable.
-add_subdirectory ("02_PlatfformerStarterKit")
+add_subdirectory ("01_blank")
+#add_subdirectory ("02_PlatfformerStarterKit")