diff --git a/docs/changelog.md b/docs/changelog.md
index 897ea74..2172db9 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -1,5 +1,14 @@
 # Changelog of the Burn-My-Windows Extension
 
+## [Burn My Window 5](https://github.com/schneegans/Burn-My-Windows/releases/tag/v5)
+
+**Release Date:** TBD
+
+#### Other Enhancements
+
+* The fire shader now uses a `smoothstep` to make it less blocky.
+
+
 ## [Burn My Window 4](https://github.com/schneegans/Burn-My-Windows/releases/tag/v4)
 
 **Release Date:** 2021-12-25
diff --git a/src/extension/FireShader.js b/src/extension/FireShader.js
index 0c61cc1..621c8dd 100644
--- a/src/extension/FireShader.js
+++ b/src/extension/FireShader.js
@@ -111,10 +111,10 @@ var FireShader = GObject.registerClass({Properties: {}, Signals: {}},
 
         // Fade at window borders.
         vec2 pos = cogl_tex_coord_in[0].st * vec2(uSizeX, uSizeY);
-        effectMask *= clamp(pos.x / edgeFadeWidth, 0, 1);
-        effectMask *= clamp(pos.y / edgeFadeWidth, 0, 1);
-        effectMask *= clamp((uSizeX - pos.x) / edgeFadeWidth, 0, 1);
-        effectMask *= clamp((uSizeY - pos.y) / edgeFadeWidth, 0, 1);
+        effectMask *= smoothstep(0, 1, clamp(pos.x / edgeFadeWidth, 0, 1));
+        effectMask *= smoothstep(0, 1, clamp(pos.y / edgeFadeWidth, 0, 1));
+        effectMask *= smoothstep(0, 1, clamp((uSizeX - pos.x) / edgeFadeWidth, 0, 1));
+        effectMask *= smoothstep(0, 1, clamp((uSizeY - pos.y) / edgeFadeWidth, 0, 1));
 
         return vec2(windowMask, effectMask);
       }