diff --git a/README.md b/README.md
index 5b8ff5b..e99ef5a 100644
--- a/README.md
+++ b/README.md
@@ -79,7 +79,7 @@ Look at the following document.
 | task02 | **Rasterization of parametric curves**<br> Quadratic Bézier curve, root of polynominal | <img src="task02/preview.png" width=100px> |
 | task03 | **Perspectively-correct texture mapping**<br>rasterization of triangle, barycentric coordinate | <img src="task03/preview.png" width=100px> |
 | task04 | **Vertex shader practice** <br>Rendering pipeline, mirror reflection, OpenGL | <img src="task04/preview.png" width=100px> |
-| task05 | TBD |  |
+| task05 | **Fragment shader practice**<br>Ray marching method, CSG modeling, implicit modeling | <img src="task05/preview.png" width=100px> |
 | task06 | TBD |  |
 | task07 | TBD |  |
 | task08 | TBD |  |
diff --git a/src/util_opengl.h b/src/util_opengl.h
index 7e98fa9..0f3325f 100644
--- a/src/util_opengl.h
+++ b/src/util_opengl.h
@@ -5,6 +5,7 @@
 #ifndef UTIL_OPENGL_H_
 #define UTIL_OPENGL_H_
 
+#include <iostream>
 #include <fstream>
 #include <vector>
 
diff --git a/task05/preview.png b/task05/preview.png
new file mode 100644
index 0000000..4aade48
Binary files /dev/null and b/task05/preview.png differ