diff --git a/src/animation-render-scheduler.spec.ts b/src/animation-render-scheduler.spec.ts
index 8c65a9d..27e97ce 100644
--- a/src/animation-render-scheduler.spec.ts
+++ b/src/animation-render-scheduler.spec.ts
@@ -1,4 +1,4 @@
-import { RenderSchedule, RenderScheduleOptions } from './render-schedule';
+import type { RenderSchedule, RenderScheduleOptions } from './render-schedule';
 import { newRenderSchedule } from './render-scheduler';
 import Mock = jest.Mock;
 import Mocked = jest.Mocked;
diff --git a/src/animation-render-scheduler.ts b/src/animation-render-scheduler.ts
index a53f2d3..6c7e0e8 100644
--- a/src/animation-render-scheduler.ts
+++ b/src/animation-render-scheduler.ts
@@ -4,7 +4,7 @@
  */
 import { customRenderScheduler } from './custom-render-scheduler';
 import { RenderQueue } from './render-queue';
-import { RenderScheduler } from './render-scheduler';
+import type { RenderScheduler } from './render-scheduler';
 
 /**
  * @internal
diff --git a/src/async-render-scheduler.spec.ts b/src/async-render-scheduler.spec.ts
index c1692d1..890b5c0 100644
--- a/src/async-render-scheduler.spec.ts
+++ b/src/async-render-scheduler.spec.ts
@@ -1,5 +1,5 @@
 import { asyncRenderScheduler } from './async-render-scheduler';
-import { RenderSchedule } from './render-schedule';
+import type { RenderSchedule } from './render-schedule';
 
 describe('asyncRenderScheduler', () => {
 
diff --git a/src/async-render-scheduler.ts b/src/async-render-scheduler.ts
index 5027dd2..0bfaab1 100644
--- a/src/async-render-scheduler.ts
+++ b/src/async-render-scheduler.ts
@@ -4,7 +4,7 @@
  */
 import { customRenderScheduler } from './custom-render-scheduler';
 import { RenderQueue } from './render-queue';
-import { RenderScheduler } from './render-scheduler';
+import type { RenderScheduler } from './render-scheduler';
 
 /**
  * @internal
diff --git a/src/custom-render-scheduler.spec.ts b/src/custom-render-scheduler.spec.ts
index bb169ad..f2759e2 100644
--- a/src/custom-render-scheduler.spec.ts
+++ b/src/custom-render-scheduler.spec.ts
@@ -1,7 +1,7 @@
 import { customRenderScheduler } from './custom-render-scheduler';
-import { RenderQueue } from './render-queue';
-import { RenderScheduleOptions } from './render-schedule';
-import { RenderExecution } from './render-shot';
+import type { RenderQueue } from './render-queue';
+import type { RenderScheduleOptions } from './render-schedule';
+import type { RenderExecution } from './render-shot';
 import Mock = jest.Mock;
 
 describe('CustomRenderScheduler', () => {
diff --git a/src/custom-render-scheduler.ts b/src/custom-render-scheduler.ts
index 07fa44f..3738ee2 100644
--- a/src/custom-render-scheduler.ts
+++ b/src/custom-render-scheduler.ts
@@ -2,10 +2,10 @@
  * @packageDocumentation
  * @module @proc7ts/render-scheduler
  */
-import { RenderQueue } from './render-queue';
+import type { RenderQueue } from './render-queue';
 import { RenderSchedule, RenderScheduleConfig, RenderScheduleOptions } from './render-schedule';
-import { RenderScheduler } from './render-scheduler';
-import { RenderExecution, RenderShot } from './render-shot';
+import type { RenderScheduler } from './render-scheduler';
+import type { RenderExecution, RenderShot } from './render-shot';
 
 /**
  * Custom render scheduler options.
diff --git a/src/immediate-render-scheduler.ts b/src/immediate-render-scheduler.ts
index abc0bbd..fe406f8 100644
--- a/src/immediate-render-scheduler.ts
+++ b/src/immediate-render-scheduler.ts
@@ -1,6 +1,6 @@
 import { RenderSchedule, RenderScheduleConfig, RenderScheduleOptions } from './render-schedule';
-import { RenderScheduler } from './render-scheduler';
-import { RenderExecution, RenderShot } from './render-shot';
+import type { RenderScheduler } from './render-scheduler';
+import type { RenderExecution, RenderShot } from './render-shot';
 
 /**
  * Render scheduler that executes render shots immediately.
diff --git a/src/manual-render-scheduler.spec.ts b/src/manual-render-scheduler.spec.ts
index b27fa19..be36903 100644
--- a/src/manual-render-scheduler.spec.ts
+++ b/src/manual-render-scheduler.spec.ts
@@ -1,5 +1,5 @@
 import { ManualRenderScheduler, newManualRenderScheduler } from './manual-render-scheduler';
-import { RenderSchedule } from './render-schedule';
+import type { RenderSchedule } from './render-schedule';
 
 describe('manualRenderScheduler', () => {
 
diff --git a/src/manual-render-scheduler.ts b/src/manual-render-scheduler.ts
index 67036dc..5e84989 100644
--- a/src/manual-render-scheduler.ts
+++ b/src/manual-render-scheduler.ts
@@ -4,7 +4,7 @@
  */
 import { customRenderScheduler } from './custom-render-scheduler';
 import { RenderQueue } from './render-queue';
-import { RenderScheduler } from './render-scheduler';
+import type { RenderScheduler } from './render-scheduler';
 
 /**
  * A render scheduler that executes scheduled render shots on request.
diff --git a/src/noop-render-scheduler.spec.ts b/src/noop-render-scheduler.spec.ts
index 014c4ca..c3582ff 100644
--- a/src/noop-render-scheduler.spec.ts
+++ b/src/noop-render-scheduler.spec.ts
@@ -1,5 +1,5 @@
 import { noopRenderScheduler } from './noop-render-scheduler';
-import { RenderSchedule } from './render-schedule';
+import type { RenderSchedule } from './render-schedule';
 
 describe('noopRenderScheduler', () => {
 
diff --git a/src/noop-render-scheduler.ts b/src/noop-render-scheduler.ts
index 4080c81..1082ebd 100644
--- a/src/noop-render-scheduler.ts
+++ b/src/noop-render-scheduler.ts
@@ -2,8 +2,8 @@
  * @packageDocumentation
  * @module @proc7ts/render-scheduler
  */
-import { RenderSchedule } from './render-schedule';
-import { RenderScheduler } from './render-scheduler';
+import type { RenderSchedule } from './render-schedule';
+import type { RenderScheduler } from './render-scheduler';
 
 /**
  * @internal
diff --git a/src/queued-render-scheduler.spec.ts b/src/queued-render-scheduler.spec.ts
index 19be1ff..112ebe2 100644
--- a/src/queued-render-scheduler.spec.ts
+++ b/src/queued-render-scheduler.spec.ts
@@ -1,5 +1,5 @@
 import { queuedRenderScheduler } from './queued-render-scheduler';
-import { RenderSchedule } from './render-schedule';
+import type { RenderSchedule } from './render-schedule';
 import Mock = jest.Mock;
 
 describe('queuedRenderScheduler', () => {
diff --git a/src/queued-render-scheduler.ts b/src/queued-render-scheduler.ts
index 50b21fc..8f73f9f 100644
--- a/src/queued-render-scheduler.ts
+++ b/src/queued-render-scheduler.ts
@@ -4,7 +4,7 @@
  */
 import { customRenderScheduler } from './custom-render-scheduler';
 import { RenderQueue } from './render-queue';
-import { RenderScheduler } from './render-scheduler';
+import type { RenderScheduler } from './render-scheduler';
 
 /**
  * @internal
diff --git a/src/render-queue.ts b/src/render-queue.ts
index 97cc3c2..8405e2b 100644
--- a/src/render-queue.ts
+++ b/src/render-queue.ts
@@ -2,7 +2,7 @@
  * @packageDocumentation
  * @module @proc7ts/render-scheduler
  */
-import { RenderShot } from './render-shot';
+import type { RenderShot } from './render-shot';
 
 /**
  * A queue of scheduled render shots.
diff --git a/src/render-schedule.ts b/src/render-schedule.ts
index 12ef881..62b99fd 100644
--- a/src/render-schedule.ts
+++ b/src/render-schedule.ts
@@ -2,7 +2,7 @@
  * @packageDocumentation
  * @module @proc7ts/render-scheduler
  */
-import { RenderShot } from './render-shot';
+import type { RenderShot } from './render-shot';
 
 /**
  * Render schedule signature.
diff --git a/src/render-scheduler.spec.ts b/src/render-scheduler.spec.ts
index 6e2307c..d256510 100644
--- a/src/render-scheduler.spec.ts
+++ b/src/render-scheduler.spec.ts
@@ -1,4 +1,4 @@
-import { RenderSchedule, RenderScheduleOptions } from './render-schedule';
+import type { RenderSchedule, RenderScheduleOptions } from './render-schedule';
 import { newRenderSchedule, RenderScheduler, setRenderScheduler } from './render-scheduler';
 import Mock = jest.Mock;
 
diff --git a/src/render-scheduler.ts b/src/render-scheduler.ts
index 3914d7b..a618e30 100644
--- a/src/render-scheduler.ts
+++ b/src/render-scheduler.ts
@@ -3,7 +3,7 @@
  * @module @proc7ts/render-scheduler
  */
 import { animationRenderScheduler } from './animation-render-scheduler';
-import { RenderSchedule, RenderScheduleOptions } from './render-schedule';
+import type { RenderSchedule, RenderScheduleOptions } from './render-schedule';
 
 /**
  * Render scheduler signature.
diff --git a/src/render-shot.ts b/src/render-shot.ts
index 9316cf7..3574de1 100644
--- a/src/render-shot.ts
+++ b/src/render-shot.ts
@@ -2,7 +2,7 @@
  * @packageDocumentation
  * @module @proc7ts/render-scheduler
  */
-import { RenderScheduleConfig } from './render-schedule';
+import type { RenderScheduleConfig } from './render-schedule';
 
 /**
  * Render shot signature.
diff --git a/tsconfig.json b/tsconfig.json
index 6f2bb1f..021fdc9 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,20 +1,20 @@
 {
   "compilerOptions": {
-    "moduleResolution": "node",
-    "module": "es2015",
-    "target": "es2018",
+    "moduleResolution": "Node",
+    "module": "ES2015",
+    "target": "ES2018",
     "strict": true,
-    "experimentalDecorators": true,
     "noFallthroughCasesInSwitch": true,
     "noImplicitReturns": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "forceConsistentCasingInFileNames": true,
     "importHelpers": true,
+    "importsNotUsedAsValues": "error",
     "noEmitHelpers": true,
     "lib": [
-      "dom",
-      "es2018"
+      "DOM",
+      "ES2018"
     ],
     "types": [
       "jest"