diff --git a/src/components/shader.hpp b/src/components/shader.hpp
index 9ac44e0..58c74c1 100644
--- a/src/components/shader.hpp
+++ b/src/components/shader.hpp
@@ -1,3 +1,7 @@
+#ifndef SHADER_HPP
+#define SHADER_HPP
+
+#define SHADER_HPP
 #include <GL/glew.h>
 #include <string>
 
@@ -24,3 +28,5 @@ class FragmentShader : public Shader {
 public:
   FragmentShader();
 };
+
+#endif // SHADER_HPP
diff --git a/src/systems/shadersystem.hpp b/src/systems/shadersystem.hpp
index d211dee..c8367fb 100644
--- a/src/systems/shadersystem.hpp
+++ b/src/systems/shadersystem.hpp
@@ -1,3 +1,6 @@
+#ifndef SHADERSYSTEM_HPP
+#define SHADERSYSTEM_HPP
+
 #include <GL/glew.h>
 #include <linmath.h>
 
@@ -14,3 +17,5 @@ public:
   int Draw(int width, int height, float time);
   GLuint *CreateBuffer();
 };
+
+#endif // SHADERSYSTEM_HPP
diff --git a/src/systems/windowsystem.hpp b/src/systems/windowsystem.hpp
index f7de070..ac26f60 100644
--- a/src/systems/windowsystem.hpp
+++ b/src/systems/windowsystem.hpp
@@ -1,3 +1,6 @@
+#ifndef WINDOWSYSTEM_HPP
+#define WINDOWSYSTEM_HPP
+
 #define GLFW_INCLUDE_NONE
 #include <GLFW/glfw3.h>
 #include "shadersystem.hpp"
@@ -10,3 +13,5 @@ public:
   WindowSystem(GLFWwindow *window, class ShaderSystem shaderSystem);
   int Loop();
 };
+
+#endif // WINDOWSYSTEM_HPP