diff --git a/src/extended-css/extended-css.ts b/src/extended-css/extended-css.ts
index 7af5a932..431e5012 100644
--- a/src/extended-css/extended-css.ts
+++ b/src/extended-css/extended-css.ts
@@ -91,6 +91,8 @@ export class ExtendedCss {
 
     private applyRulesScheduler: AsyncWrapper;
 
+    private applyRulesCallbackListener: () => void;
+
     // Instance of ExtCssDocument is needed for using selector-ast cache
     extCssDocument: ExtCssDocument;
 
@@ -128,6 +130,10 @@ export class ExtendedCss {
         if (this.context.beforeStyleApplied && typeof this.context.beforeStyleApplied !== 'function') {
             throw new Error(`Invalid configuration. Type of 'beforeStyleApplied' should be a function, received: '${typeof this.context.beforeStyleApplied}'`); // eslint-disable-line max-len
         }
+
+        this.applyRulesCallbackListener = () => {
+            applyRules(this.context);
+        };
     }
 
     /**
@@ -139,7 +145,7 @@ export class ExtendedCss {
         if (document.readyState !== 'complete') {
             document.addEventListener(
                 'DOMContentLoaded',
-                () => { applyRules(this.context); },
+                this.applyRulesCallbackListener,
                 false,
             );
         }
@@ -153,6 +159,11 @@ export class ExtendedCss {
         this.context.affectedElements.forEach((el) => {
             revertStyle(el);
         });
+        document.removeEventListener(
+            'DOMContentLoaded',
+            this.applyRulesCallbackListener,
+            false,
+        );
     }
 
     /**
diff --git a/src/extended-css/helpers/document-observer.ts b/src/extended-css/helpers/document-observer.ts
index 77e51991..c7cb9df0 100644
--- a/src/extended-css/helpers/document-observer.ts
+++ b/src/extended-css/helpers/document-observer.ts
@@ -22,6 +22,9 @@ const observeDocument = (context: Context, callback: MainCallback): void => {
             if (eventTracker.isIgnoredEventType() && shouldIgnoreMutations(mutations)) {
                 return;
             }
+            // save instance of EventTracker to context
+            // for removing its event listeners on disconnectDocument() while mainDisconnect()
+            context.eventTracker = eventTracker;
             callback();
         }));
         context.domMutationObserver.observe(document, {
@@ -45,6 +48,8 @@ const disconnectDocument = (context: Context, callback: MainCallback): void => {
         document.removeEventListener('DOMNodeRemoved', callback, false);
         document.removeEventListener('DOMAttrModified', callback, false);
     }
+    // clean up event listeners
+    context.eventTracker?.stopTracking();
 };
 
 export const mainObserve = (context: Context, mainCallback: MainCallback): void => {
diff --git a/src/extended-css/helpers/event-tracker.ts b/src/extended-css/helpers/event-tracker.ts
index b14d7ed5..909225ad 100644
--- a/src/extended-css/helpers/event-tracker.ts
+++ b/src/extended-css/helpers/event-tracker.ts
@@ -25,8 +25,6 @@ const SAFARI_PROBLEMATIC_EVENTS = ['wheel'];
 export class EventTracker {
     private trackedEvents: string[];
 
-    private lastEvent?: Event;
-
     private lastEventType?: string;
 
     private lastEventTime?: number;
@@ -42,7 +40,6 @@ export class EventTracker {
     }
 
     private trackEvent(event: Event): void {
-        this.lastEvent = event;
         this.lastEventType = event.type;
         this.lastEventTime = Date.now();
     }
@@ -64,4 +61,10 @@ export class EventTracker {
             && !!sinceLastEventTime
             && sinceLastEventTime < LAST_EVENT_TIMEOUT_MS;
     }
+
+    stopTracking(): void {
+        this.trackedEvents.forEach((eventName) => {
+            document.documentElement.removeEventListener(eventName, this.trackEvent, true);
+        });
+    }
 }
diff --git a/src/extended-css/helpers/types.ts b/src/extended-css/helpers/types.ts
index 86603075..6390c5b9 100644
--- a/src/extended-css/helpers/types.ts
+++ b/src/extended-css/helpers/types.ts
@@ -1,4 +1,5 @@
 import { CssStyleMap, ExtCssRuleData } from '../../stylesheet';
+import { EventTracker } from './event-tracker';
 import { ExtMutationObserver } from './mutation-observer';
 
 export type MainCallback = () => void;
@@ -78,6 +79,11 @@ export interface Context {
      */
     isDomObserved: boolean;
 
+    /**
+     * Instance of EventTracker for document observing
+     */
+    eventTracker?: EventTracker;
+
     /**
      * Main document mutation observer
      */