diff --git a/21-framebuffers/shaders/21-screen-kernel.frag.glsl b/21-framebuffers/shaders/21-screen-kernel.frag.glsl
new file mode 100644
index 0000000..ec8fbeb
--- /dev/null
+++ b/21-framebuffers/shaders/21-screen-kernel.frag.glsl
@@ -0,0 +1,38 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec2 TexCoords;
+
+uniform sampler2D screenTexture;
+
+const float offset = 1.0 / 300.0;
+
+void main()
+{
+  vec2 offsets[9] = vec2[](
+      vec2(-offset,  offset), // top-left
+      vec2( 0.0f,    offset), // top-center
+      vec2( offset,  offset), // top-right
+      vec2(-offset,  0.0f),   // center-left
+      vec2( 0.0f,    0.0f),   // center-center
+      vec2( offset,  0.0f),   // center-right
+      vec2(-offset, -offset), // bottom-left
+      vec2( 0.0f,   -offset), // bottom-center
+      vec2( offset, -offset)  // bottom-right
+      );
+
+  float kernel[9] = float[](
+      1.0 / 16, 2.0 / 16, 1.0 / 16,
+      2.0 / 16, 4.0 / 16, 2.0 / 16,
+      1.0 / 16, 2.0 / 16, 1.0 / 16
+  );
+
+  vec3 col = vec3(0.0);
+
+  for(int i = 0; i < 9; i++) {
+    vec3 sampleTex = vec3(texture(screenTexture, TexCoords.st + offsets[i]));
+    col += sampleTex * kernel[i];
+  }
+
+  FragColor = vec4(col, 1.0);
+}
diff --git a/21-framebuffers/src/scene.hpp b/21-framebuffers/src/scene.hpp
index ebc9450..edc4f39 100644
--- a/21-framebuffers/src/scene.hpp
+++ b/21-framebuffers/src/scene.hpp
@@ -41,7 +41,7 @@ struct Scene {
 
   Scene(components::Scene& config):
     shader{config.shader.vertex_path, config.shader.frag_path},
-    screen{.shader={config.screen_shader.vertex_path, config.shader.frag_path}},
+    screen{.shader={config.screen_shader.vertex_path, config.screen_shader.frag_path}},
     materials{config.materials},
     camera{
       .position=config.camera.position,
diff --git a/21-framebuffers/src/shader.cpp b/21-framebuffers/src/shader.cpp
index d51ee0b..e965c61 100644
--- a/21-framebuffers/src/shader.cpp
+++ b/21-framebuffers/src/shader.cpp
@@ -43,6 +43,7 @@ void check_error(const std::string& what, unsigned int thing, GLenum check_type)
 }
 
 unsigned int Shader::load_shader(const std::string& filename, GLenum shader_type) {
+  dbc::log($F("Loading shader {}", filename));
   dbc::check(fs::exists(filename),
       std::format("shader file {} does not exist", filename));