diff --git a/src/vs/workbench/api/electron-browser/mainThreadTerminalService.ts b/src/vs/workbench/api/electron-browser/mainThreadTerminalService.ts
index ccf129ce117..c25e31ae085 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadTerminalService.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadTerminalService.ts
@@ -16,6 +16,8 @@ export class MainThreadTerminalService implements MainThreadTerminalServiceShape
 	private _proxy: ExtHostTerminalServiceShape;
 	private _toDispose: IDisposable[] = [];
 	private _terminalProcesses: { [id: number]: ITerminalProcessExtHostProxy } = {};
+	private _terminalOnDidWriteDataListeners: { [id: number]: IDisposable } = {};
+	private _terminalOnDidAcceptInputListeners: { [id: number]: IDisposable } = {};
 
 	constructor(
 		extHostContext: IExtHostContext,
@@ -114,9 +116,18 @@ export class MainThreadTerminalService implements MainThreadTerminalServiceShape
 
 	public $terminalRendererRegisterOnInputListener(terminalId: number): void {
 		const terminalInstance = this.terminalService.getInstanceFromId(terminalId);
-		if (terminalInstance) {
-			terminalInstance.addDisposable(terminalInstance.onRendererInput(data => this._onTerminalRendererInput(terminalId, data)));
+		if (!terminalInstance) {
+			return;
 		}
+
+		// Listener already registered
+		if (this._terminalOnDidAcceptInputListeners.hasOwnProperty(terminalId)) {
+			return;
+		}
+
+		// Register
+		this._terminalOnDidAcceptInputListeners[terminalId] = terminalInstance.onRendererInput(data => this._onTerminalRendererInput(terminalId, data));
+		terminalInstance.addDisposable(this._terminalOnDidAcceptInputListeners[terminalId]);
 	}
 
 	public $sendText(terminalId: number, text: string, addNewLine: boolean): void {
@@ -128,11 +139,20 @@ export class MainThreadTerminalService implements MainThreadTerminalServiceShape
 
 	public $registerOnDataListener(terminalId: number): void {
 		const terminalInstance = this.terminalService.getInstanceFromId(terminalId);
-		if (terminalInstance) {
-			terminalInstance.addDisposable(terminalInstance.onData(data => {
-				this._onTerminalData(terminalId, data);
-			}));
+		if (!terminalInstance) {
+			return;
 		}
+
+		// Listener already registered
+		if (this._terminalOnDidWriteDataListeners[terminalId]) {
+			return;
+		}
+
+		// Register
+		this._terminalOnDidWriteDataListeners[terminalId] = terminalInstance.onData(data => {
+			this._onTerminalData(terminalId, data);
+		});
+		terminalInstance.addDisposable(this._terminalOnDidWriteDataListeners[terminalId]);
 	}
 
 	private _onActiveTerminalChanged(terminalId: number | undefined): void {