diff --git a/src/InputHandler.ts b/src/InputHandler.ts
index c5c165017..7732d4cf7 100644
--- a/src/InputHandler.ts
+++ b/src/InputHandler.ts
@@ -1771,7 +1771,7 @@ export class InputHandler extends Disposable implements IInputHandler {
         case 1004: // send focusin/focusout events
           // focusin: ^[[I
           // focusout: ^[[O
-          this._terminal.sendFocus = true;
+          this._coreService.decPrivateModes.sendFocus = true;
           break;
         case 1005: // utf8 ext mode mouse - removed in #2507
           this._logService.debug('DECSET 1005 not supported (see #2507)');
@@ -1986,7 +1986,7 @@ export class InputHandler extends Disposable implements IInputHandler {
           this._coreMouseService.activeProtocol = 'NONE';
           break;
         case 1004: // send focusin/focusout events
-          this._terminal.sendFocus = false;
+          this._coreService.decPrivateModes.sendFocus = false;
           break;
         case 1005: // utf8 ext mode mouse - removed in #2507
           this._logService.debug('DECRST 1005 not supported (see #2507)');
diff --git a/src/Terminal.ts b/src/Terminal.ts
index 5c2bbd7d8..bb02671fd 100644
--- a/src/Terminal.ts
+++ b/src/Terminal.ts
@@ -90,7 +90,6 @@ export class Terminal extends CoreTerminal implements ITerminal, IInputHandlingT
 
   // mouse properties
   public mouseEvents: CoreMouseEventType = CoreMouseEventType.NONE;
-  public sendFocus: boolean;
 
   // write buffer
   private _writeBuffer: WriteBuffer;
@@ -277,7 +276,7 @@ export class Terminal extends CoreTerminal implements ITerminal, IInputHandlingT
    * Binds the desired focus behavior on a given terminal object.
    */
   private _onTextAreaFocus(ev: KeyboardEvent): void {
-    if (this.sendFocus) {
+    if (this._coreService.decPrivateModes.sendFocus) {
       this._coreService.triggerDataEvent(C0.ESC + '[I');
     }
     this.updateCursorStyle(ev);
@@ -302,7 +301,7 @@ export class Terminal extends CoreTerminal implements ITerminal, IInputHandlingT
     // screen readers reading it out.
     this.textarea.value = '';
     this.refresh(this.buffer.y, this.buffer.y);
-    if (this.sendFocus) {
+    if (this._coreService.decPrivateModes.sendFocus) {
       this._coreService.triggerDataEvent(C0.ESC + '[O');
     }
     this.element.classList.remove('focus');
diff --git a/src/TestUtils.test.ts b/src/TestUtils.test.ts
index ea0a58844..c15ce5607 100644
--- a/src/TestUtils.test.ts
+++ b/src/TestUtils.test.ts
@@ -203,7 +203,6 @@ export class MockTerminal implements ITerminal {
 export class MockInputHandlingTerminal implements IInputHandlingTerminal {
   public onA11yCharEmitter: EventEmitter<string>;
   public onA11yTabEmitter: EventEmitter<number>;
-  public sendFocus: boolean;
   public buffers: IBufferSet;
   public buffer: IBuffer = new MockBuffer();
   public viewport: IViewport;
diff --git a/src/Types.d.ts b/src/Types.d.ts
index a2000551f..15eda648d 100644
--- a/src/Types.d.ts
+++ b/src/Types.d.ts
@@ -21,8 +21,6 @@ export type LineData = CharData[];
  * InputHandler cleanly from the ITerminal interface.
  */
 export interface IInputHandlingTerminal {
-  sendFocus: boolean;
-
   buffers: IBufferSet;
   buffer: IBuffer;
   viewport: IViewport;
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index 389c53822..55df896ee 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,6 +66,7 @@ export class MockCoreService implements ICoreService {
     applicationKeypad: false,
     bracketedPasteMode: false,
     origin: false,
+    sendFocus: false,
     wraparound: true
   };
   public onData: IEvent<string> = new EventEmitter<string>().event;
diff --git a/src/common/Types.d.ts b/src/common/Types.d.ts
index 1d616f54f..cc7928c30 100644
--- a/src/common/Types.d.ts
+++ b/src/common/Types.d.ts
@@ -168,6 +168,7 @@ export interface IDecPrivateModes {
   applicationKeypad: boolean;
   bracketedPasteMode: boolean;
   origin: boolean;
+  sendFocus: boolean;
   wraparound: boolean; // defaults: xterm - true, vt100 - false
 }
 
diff --git a/src/common/services/CoreService.ts b/src/common/services/CoreService.ts
index 285532b5d..55d425aa3 100644
--- a/src/common/services/CoreService.ts
+++ b/src/common/services/CoreService.ts
@@ -17,6 +17,7 @@ const DEFAULT_DEC_PRIVATE_MODES: IDecPrivateModes = Object.freeze({
   applicationKeypad: false,
   bracketedPasteMode: false,
   origin: false,
+  sendFocus: false,
   wraparound: true // defaults: xterm - true, vt100 - false
 });