diff --git a/src/controller/index.ts b/src/controller/index.ts
index a731c070..0bc3f414 100644
--- a/src/controller/index.ts
+++ b/src/controller/index.ts
@@ -348,7 +348,7 @@ export class TilingController implements Controller {
     window.timestamp = new Date().getTime();
   }
 
-  public onShortcut(input: Shortcut, data?: any): void {
+  public onShortcut(input: Shortcut, data?: string): void {
     if (this.config.directionalKeyMode === "focus") {
       switch (input) {
         case Shortcut.Up:
diff --git a/src/driver/surface.ts b/src/driver/surface.ts
index 79d51efd..949f1eae 100644
--- a/src/driver/surface.ts
+++ b/src/driver/surface.ts
@@ -24,10 +24,10 @@ export class KWinSurface implements DriverSurface {
   ): string {
     let path = String(screen);
     if (config.layoutPerActivity) {
-      path += "@" + activity;
+      path += `@${activity}`;
     }
     if (config.layoutPerDesktop) {
-      path += "#" + desktop;
+      path += `"#${desktop}`;
     }
     return path;
   }
diff --git a/src/engine/index.ts b/src/engine/index.ts
index 6a83aaa2..2edb5360 100644
--- a/src/engine/index.ts
+++ b/src/engine/index.ts
@@ -308,7 +308,7 @@ export class TilingEngine implements Engine {
    * which is straight against the purpose of tiling WM. This operation
    * move/resize such windows back to where/how they should be.
    */
-  public enforceSize(window: Window) {
+  public enforceSize(window: Window): void {
     if (window.tiled && !window.actualGeometry.equals(window.geometry)) {
       qmlSetTimeout(() => {
         if (window.tiled) {
@@ -566,7 +566,7 @@ export class TilingEngine implements Engine {
    *
    * @returns True if the layout overrides the shortcut. False, otherwise.
    */
-  public handleLayoutShortcut(input: Shortcut, data?: any): boolean {
+  public handleLayoutShortcut(input: Shortcut, data?: string): boolean {
     const layout = this.layouts.getCurrentLayout(
       this.controller.currentSurface
     );
diff --git a/src/engine/layout/cascade_layout.ts b/src/engine/layout/cascade_layout.ts
index 7ff276f7..7760d9f1 100644
--- a/src/engine/layout/cascade_layout.ts
+++ b/src/engine/layout/cascade_layout.ts
@@ -95,7 +95,11 @@ export default class CascadeLayout implements WindowsLayout {
     return new CascadeLayout(this.dir);
   }
 
-  public handleShortcut(engine: Engine, input: Shortcut, _data?: any): boolean {
+  public handleShortcut(
+    engine: Engine,
+    input: Shortcut,
+    _data?: string
+  ): boolean {
     switch (input) {
       case Shortcut.Increase:
         this.dir = (this.dir + 1 + 8) % 8;
diff --git a/src/engine/layout/layout_part.ts b/src/engine/layout/layout_part.ts
index cbe6146c..d36e8078 100644
--- a/src/engine/layout/layout_part.ts
+++ b/src/engine/layout/layout_part.ts
@@ -33,7 +33,7 @@ export class FillLayoutPart implements ILayoutPart {
   }
 
   public apply(area: Rect, tiles: Window[]): Rect[] {
-    return tiles.map((tile) => {
+    return tiles.map((_tile) => {
       return area;
     });
   }
@@ -245,7 +245,7 @@ export class RotateLayoutPart<T extends ILayoutPart> implements ILayoutPart {
 
     switch (this.angle) {
       case 0:
-        delta = delta;
+        // No adjustment needed
         break;
       case 90:
         delta = new RectDelta(delta.south, delta.north, delta.east, delta.west);
diff --git a/src/engine/layout/monocle_layout.ts b/src/engine/layout/monocle_layout.ts
index 37091a3c..b596994e 100644
--- a/src/engine/layout/monocle_layout.ts
+++ b/src/engine/layout/monocle_layout.ts
@@ -60,7 +60,11 @@ export default class MonocleLayout implements WindowsLayout {
     return this;
   }
 
-  public handleShortcut(engine: Engine, input: Shortcut, _data?: any): boolean {
+  public handleShortcut(
+    engine: Engine,
+    input: Shortcut,
+    _data?: string
+  ): boolean {
     switch (input) {
       case Shortcut.Up:
       case Shortcut.FocusUp:
diff --git a/src/engine/layout/three_column_layout.ts b/src/engine/layout/three_column_layout.ts
index 9a2e79cf..cd524297 100644
--- a/src/engine/layout/three_column_layout.ts
+++ b/src/engine/layout/three_column_layout.ts
@@ -197,7 +197,11 @@ export default class ThreeColumnLayout implements WindowsLayout {
     return other;
   }
 
-  public handleShortcut(engine: Engine, input: Shortcut, _data?: any): boolean {
+  public handleShortcut(
+    engine: Engine,
+    input: Shortcut,
+    _data?: string
+  ): boolean {
     switch (input) {
       case Shortcut.Increase:
         this.resizeMaster(engine, +1);