diff --git a/news/3 Code Health/642.md b/news/3 Code Health/642.md
new file mode 100644
index 000000000000..8786ca0bf04f
--- /dev/null
+++ b/news/3 Code Health/642.md	
@@ -0,0 +1 @@
+Expose an event to notify changes to settings instead of casting settings to concrete class.
diff --git a/src/client/common/configSettings.ts b/src/client/common/configSettings.ts
index d890dc8c60b2..db0f5e9c55f2 100644
--- a/src/client/common/configSettings.ts
+++ b/src/client/common/configSettings.ts
@@ -1,9 +1,8 @@
 'use strict';
 
 import * as child_process from 'child_process';
-import { EventEmitter } from 'events';
 import * as path from 'path';
-import { ConfigurationChangeEvent, ConfigurationTarget, DiagnosticSeverity, Disposable, Uri, WorkspaceConfiguration } from 'vscode';
+import { ConfigurationChangeEvent, ConfigurationTarget, DiagnosticSeverity, Disposable, Event, EventEmitter, Uri, WorkspaceConfiguration } from 'vscode';
 import '../common/extensions';
 import { IInterpreterAutoSeletionProxyService } from '../interpreter/autoSelection/types';
 import { sendTelemetryEvent } from '../telemetry';
@@ -30,7 +29,8 @@ import { SystemVariables } from './variables/systemVariables';
 // tslint:disable:no-require-imports no-var-requires
 const untildify = require('untildify');
 
-export class PythonSettings extends EventEmitter implements IPythonSettings {
+// tslint:disable-next-line:completed-docs
+export class PythonSettings implements IPythonSettings {
     private static pythonSettings: Map<string, PythonSettings> = new Map<string, PythonSettings>();
     public downloadLanguageServer = true;
     public jediEnabled = true;
@@ -55,15 +55,18 @@ export class PythonSettings extends EventEmitter implements IPythonSettings {
     public autoUpdateLanguageServer: boolean = true;
     public datascience!: IDataScienceSettings;
 
+    protected readonly changed = new EventEmitter<void>();
     private workspaceRoot: Uri;
     private disposables: Disposable[] = [];
     // tslint:disable-next-line:variable-name
     private _pythonPath = '';
     private readonly workspace: IWorkspaceService;
+    public get onDidChange(): Event<void> {
+        return this.changed.event;
+    }
 
     constructor(workspaceFolder: Uri | undefined, private readonly InterpreterAutoSelectionService: IInterpreterAutoSeletionProxyService,
         workspace?: IWorkspaceService) {
-        super();
         this.workspace = workspace || new WorkspaceService();
         this.workspaceRoot = workspaceFolder ? workspaceFolder : Uri.file(__dirname);
         this.initialize();
@@ -393,7 +396,7 @@ export class PythonSettings extends EventEmitter implements IPythonSettings {
     }
     @debounce(1)
     protected debounceChangeNotification() {
-        this.emit('change');
+        this.changed.fire();
     }
 }
 
diff --git a/src/client/common/types.ts b/src/client/common/types.ts
index b90d9eec5ff5..7563697d85ef 100644
--- a/src/client/common/types.ts
+++ b/src/client/common/types.ts
@@ -3,7 +3,7 @@
 'use strict';
 
 import { Socket } from 'net';
-import { ConfigurationTarget, DiagnosticSeverity, Disposable, Extension, ExtensionContext, OutputChannel, Uri, WorkspaceEdit } from 'vscode';
+import { ConfigurationTarget, DiagnosticSeverity, Disposable, Event, Extension, ExtensionContext, OutputChannel, Uri, WorkspaceEdit } from 'vscode';
 import { EnvironmentVariables } from './variables/types';
 export const IOutputChannel = Symbol('IOutputChannel');
 export interface IOutputChannel extends OutputChannel { }
@@ -160,6 +160,7 @@ export interface IPythonSettings {
     readonly analysis: IAnalysisSettings;
     readonly autoUpdateLanguageServer: boolean;
     readonly datascience: IDataScienceSettings;
+    readonly onDidChange: Event<void>;
 }
 export interface ISortImportSettings {
     readonly path: string;
diff --git a/src/client/datascience/datascience.ts b/src/client/datascience/datascience.ts
index 06a6396c8d70..9442a101d69e 100644
--- a/src/client/datascience/datascience.ts
+++ b/src/client/datascience/datascience.ts
@@ -8,12 +8,12 @@ import { URL } from 'url';
 import * as vscode from 'vscode';
 
 import { IApplicationShell, ICommandManager, IDocumentManager } from '../common/application/types';
-import { PythonSettings } from '../common/configSettings';
 import { PYTHON, PYTHON_LANGUAGE } from '../common/constants';
 import { ContextKey } from '../common/contextKey';
 import {
     BANNER_NAME_DS_SURVEY,
     IConfigurationService,
+    IDisposable,
     IDisposableRegistry,
     IExtensionContext,
     IPythonExtensionBanner
@@ -30,6 +30,7 @@ export class DataScience implements IDataScience {
     public isDisposed: boolean = false;
     private readonly commandListeners: IDataScienceCommandListener[];
     private readonly dataScienceSurveyBanner: IPythonExtensionBanner;
+    private changeHandler: IDisposable | undefined;
     constructor(@inject(IServiceContainer) private serviceContainer: IServiceContainer,
         @inject(ICommandManager) private commandManager: ICommandManager,
         @inject(IDisposableRegistry) private disposableRegistry: IDisposableRegistry,
@@ -38,8 +39,8 @@ export class DataScience implements IDataScience {
         @inject(IConfigurationService) private configuration: IConfigurationService,
         @inject(IDocumentManager) private documentManager: IDocumentManager,
         @inject(IApplicationShell) private appShell: IApplicationShell) {
-            this.commandListeners = this.serviceContainer.getAll<IDataScienceCommandListener>(IDataScienceCommandListener);
-            this.dataScienceSurveyBanner = this.serviceContainer.get<IPythonExtensionBanner>(IPythonExtensionBanner, BANNER_NAME_DS_SURVEY);
+        this.commandListeners = this.serviceContainer.getAll<IDataScienceCommandListener>(IDataScienceCommandListener);
+        this.dataScienceSurveyBanner = this.serviceContainer.get<IPythonExtensionBanner>(IPythonExtensionBanner, BANNER_NAME_DS_SURVEY);
     }
 
     public async activate(): Promise<void> {
@@ -53,7 +54,7 @@ export class DataScience implements IDataScience {
 
         // Set our initial settings and sign up for changes
         this.onSettingsChanged();
-        (this.configuration.getSettings() as PythonSettings).addListener('change', this.onSettingsChanged);
+        this.changeHandler = this.configuration.getSettings().onDidChange(this.onSettingsChanged.bind(this));
         this.disposableRegistry.push(this);
 
         // Listen for active editor changes so we can detect have code cells or not
@@ -62,9 +63,9 @@ export class DataScience implements IDataScience {
     }
 
     public async dispose() {
-        if (!this.isDisposed) {
-            this.isDisposed = true;
-            (this.configuration.getSettings() as PythonSettings).removeListener('change', this.onSettingsChanged);
+        if (this.changeHandler) {
+            this.changeHandler.dispose();
+            this.changeHandler = undefined;
         }
     }
 
@@ -121,13 +122,13 @@ export class DataScience implements IDataScience {
         switch (selection) {
             case localize.DataScience.jupyterSelectURILaunchLocal():
                 return this.setJupyterURIToLocal();
-            break;
+                break;
             case localize.DataScience.jupyterSelectURISpecifyURI():
                 return this.selectJupyterLaunchURI();
-            break;
+                break;
             default:
                 // If user cancels quick pick we will get undefined as the selection and fall through here
-            break;
+                break;
         }
     }
 
@@ -139,8 +140,10 @@ export class DataScience implements IDataScience {
     @captureTelemetry(Telemetry.SetJupyterURIToUserSpecified)
     private async selectJupyterLaunchURI(): Promise<void> {
         // First get the proposed URI from the user
-        const userURI = await this.appShell.showInputBox({prompt: localize.DataScience.jupyterSelectURIPrompt(),
-            placeHolder: 'https://hostname:8080/?token=849d61a414abafab97bc4aab1f3547755ddc232c2b8cb7fe', validateInput: this.validateURI, ignoreFocusOut: true});
+        const userURI = await this.appShell.showInputBox({
+            prompt: localize.DataScience.jupyterSelectURIPrompt(),
+            placeHolder: 'https://hostname:8080/?token=849d61a414abafab97bc4aab1f3547755ddc232c2b8cb7fe', validateInput: this.validateURI, ignoreFocusOut: true
+        });
 
         if (userURI) {
             await this.configuration.updateSetting('dataScience.jupyterServerURI', userURI, undefined, vscode.ConfigurationTarget.Workspace);
@@ -149,8 +152,8 @@ export class DataScience implements IDataScience {
 
     private validateURI = (testURI: string): string | undefined | null => {
         try {
-           // tslint:disable-next-line:no-unused-expression
-           new URL(testURI);
+            // tslint:disable-next-line:no-unused-expression
+            new URL(testURI);
         } catch {
             return localize.DataScience.jupyterSelectURIInvalidURI();
         }
@@ -169,8 +172,7 @@ export class DataScience implements IDataScience {
     // Get our matching code watcher for the active document
     private getCurrentCodeWatcher(): ICodeWatcher | undefined {
         const activeEditor = vscode.window.activeTextEditor;
-        if (!activeEditor || !activeEditor.document)
-        {
+        if (!activeEditor || !activeEditor.document) {
             return undefined;
         }
 
diff --git a/src/client/datascience/history.ts b/src/client/datascience/history.ts
index cdf44090ca93..dc0593359a0d 100644
--- a/src/client/datascience/history.ts
+++ b/src/client/datascience/history.ts
@@ -21,11 +21,10 @@ import {
     IWorkspaceService
 } from '../common/application/types';
 import { CancellationError } from '../common/cancellation';
-import { PythonSettings } from '../common/configSettings';
 import { EXTENSION_ROOT_DIR } from '../common/constants';
 import { ContextKey } from '../common/contextKey';
 import { IFileSystem } from '../common/platform/types';
-import { IConfigurationService, IDisposableRegistry, ILogger } from '../common/types';
+import { IConfigurationService, IDisposable, IDisposableRegistry, ILogger } from '../common/types';
 import { createDeferred } from '../common/utils/async';
 import * as localize from '../common/utils/localize';
 import { IInterpreterService } from '../interpreter/contracts';
@@ -54,18 +53,19 @@ export enum SysInfoReason {
 
 @injectable()
 export class History implements IWebPanelMessageListener, IHistory {
-    private disposed : boolean = false;
-    private webPanel : IWebPanel | undefined;
+    private disposed: boolean = false;
+    private webPanel: IWebPanel | undefined;
     private loadPromise: Promise<void>;
-    private interpreterChangedDisposable : Disposable;
-    private closedEvent : EventEmitter<IHistory>;
+    private interpreterChangedDisposable: Disposable;
+    private closedEvent: EventEmitter<IHistory>;
     private unfinishedCells: ICell[] = [];
     private restartingKernel: boolean = false;
     private potentiallyUnfinishedStatus: Disposable[] = [];
     private addedSysInfo: boolean = false;
     private ignoreCount: number = 0;
-    private waitingForExportCells : boolean = false;
+    private waitingForExportCells: boolean = false;
     private jupyterServer: INotebookServer | undefined;
+    private changeHandler: IDisposable | undefined;
 
     constructor(
         @inject(IApplicationShell) private applicationShell: IApplicationShell,
@@ -73,9 +73,9 @@ export class History implements IWebPanelMessageListener, IHistory {
         @inject(IInterpreterService) private interpreterService: IInterpreterService,
         @inject(IWebPanelProvider) private provider: IWebPanelProvider,
         @inject(IDisposableRegistry) private disposables: IDisposableRegistry,
-        @inject(ICodeCssGenerator) private cssGenerator : ICodeCssGenerator,
-        @inject(ILogger) private logger : ILogger,
-        @inject(IStatusProvider) private statusProvider : IStatusProvider,
+        @inject(ICodeCssGenerator) private cssGenerator: ICodeCssGenerator,
+        @inject(ILogger) private logger: ILogger,
+        @inject(IStatusProvider) private statusProvider: IStatusProvider,
         @inject(IJupyterExecution) private jupyterExecution: IJupyterExecution,
         @inject(IFileSystem) private fileSystem: IFileSystem,
         @inject(IConfigurationService) private configuration: IConfigurationService,
@@ -85,7 +85,7 @@ export class History implements IWebPanelMessageListener, IHistory {
 
         // Sign up for configuration changes
         this.interpreterChangedDisposable = this.interpreterService.onDidChangeInterpreter(this.onInterpreterChanged);
-        (this.configuration.getSettings() as PythonSettings).addListener('change', this.onSettingsChanged);
+        this.changeHandler = this.configuration.getSettings().onDidChange(this.onSettingsChanged.bind(this));
 
         // Create our event emitter
         this.closedEvent = new EventEmitter<IHistory>();
@@ -95,7 +95,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         this.loadPromise = this.load();
     }
 
-    public async show() : Promise<void> {
+    public async show(): Promise<void> {
         if (!this.disposed) {
             // Make sure we're loaded first
             await this.loadPromise;
@@ -107,11 +107,11 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    public get closed() : Event<IHistory> {
+    public get closed(): Event<IHistory> {
         return this.closedEvent.event;
     }
 
-    public async addCode(code: string, file: string, line: number, editor?: TextEditor) : Promise<void> {
+    public async addCode(code: string, file: string, line: number, editor?: TextEditor): Promise<void> {
         // Start a status item
         const status = this.setStatus(localize.DataScience.executingCode());
 
@@ -179,7 +179,7 @@ export class History implements IWebPanelMessageListener, IHistory {
     // tslint:disable-next-line: no-any no-empty
     public postMessage(type: string, payload?: any) {
         if (this.webPanel) {
-            this.webPanel.postMessage({type: type, payload: payload});
+            this.webPanel.postMessage({ type: type, payload: payload });
         }
     }
 
@@ -243,17 +243,20 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    public async dispose()  {
+    public async dispose() {
         if (!this.disposed) {
             this.disposed = true;
             this.interpreterChangedDisposable.dispose();
-            (this.configuration.getSettings() as PythonSettings).removeListener('change', this.onSettingsChanged);
             this.closedEvent.fire(this);
             if (this.jupyterServer) {
                 await this.jupyterServer.shutdown();
             }
             this.updateContexts();
         }
+        if (this.changeHandler) {
+            this.changeHandler.dispose();
+            this.changeHandler = undefined;
+        }
     }
 
     @captureTelemetry(Telemetry.Undo)
@@ -345,7 +348,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    private async restartKernelInternal() : Promise<void> {
+    private async restartKernelInternal(): Promise<void> {
         this.restartingKernel = true;
 
         // First we need to finish all outstanding cells.
@@ -416,7 +419,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    private setStatus = (message: string) : Disposable => {
+    private setStatus = (message: string): Disposable => {
         const result = this.statusProvider.set(message);
         this.potentiallyUnfinishedStatus.push(result);
         return result;
@@ -434,13 +437,13 @@ export class History implements IWebPanelMessageListener, IHistory {
             copy.data.execution_count = count - this.ignoreCount;
         }
         if (this.webPanel) {
-            this.webPanel.postMessage({type: message, payload: copy});
+            this.webPanel.postMessage({ type: message, payload: copy });
         }
     }
 
-    private onAddCodeEvent = (cells : ICell[], editor?: TextEditor) => {
+    private onAddCodeEvent = (cells: ICell[], editor?: TextEditor) => {
         // Send each cell to the other side
-        cells.forEach((cell : ICell) => {
+        cells.forEach((cell: ICell) => {
             if (this.webPanel) {
                 switch (cell.state) {
                     case CellState.init:
@@ -459,7 +462,7 @@ export class History implements IWebPanelMessageListener, IHistory {
                     case CellState.error:
                     case CellState.finished:
                         // Tell the react controls we're done
-                        this.sendCell(cell,  HistoryMessages.FinishCell);
+                        this.sendCell(cell, HistoryMessages.FinishCell);
 
                         // Remove from the list of unfinished cells
                         this.unfinishedCells = this.unfinishedCells.filter(c => c.id !== cell.id);
@@ -488,7 +491,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         const dsSettings = JSON.stringify(this.configuration.getSettings().datascience);
 
         if (this.webPanel) {
-            this.webPanel.postMessage({type: HistoryMessages.UpdateSettings, payload: dsSettings});
+            this.webPanel.postMessage({ type: HistoryMessages.UpdateSettings, payload: dsSettings });
         }
     }
 
@@ -511,10 +514,10 @@ export class History implements IWebPanelMessageListener, IHistory {
     }
 
     private async gotoCodeInternal(file: string, line: number) {
-        let editor : TextEditor | undefined;
+        let editor: TextEditor | undefined;
 
         if (await fs.pathExists(file)) {
-            editor = await this.documentManager.showTextDocument(Uri.file(file), {viewColumn: ViewColumn.One});
+            editor = await this.documentManager.showTextDocument(Uri.file(file), { viewColumn: ViewColumn.One });
         } else {
             // File URI isn't going to work. Look through the active text documents
             editor = this.documentManager.visibleTextEditors.find(te => te.document.fileName === file);
@@ -532,7 +535,7 @@ export class History implements IWebPanelMessageListener, IHistory {
 
     @captureTelemetry(Telemetry.ExportNotebook, undefined, false)
     // tslint:disable-next-line: no-any no-empty
-    private export (payload: any) {
+    private export(payload: any) {
         if (payload.contents) {
             // Should be an array of cells
             const cells = payload.contents as ICell[];
@@ -556,7 +559,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    private exportToFile = async (cells: ICell[], file : string) => {
+    private exportToFile = async (cells: ICell[], file: string) => {
         // Take the list of cells, convert them to a notebook json format and write to disk
         if (this.jupyterServer) {
             let directoryChange;
@@ -569,8 +572,8 @@ export class History implements IWebPanelMessageListener, IHistory {
 
             try {
                 // tslint:disable-next-line: no-any
-                await this.fileSystem.writeFile(file, JSON.stringify(notebook), {encoding: 'utf8', flag: 'w'});
-                this.applicationShell.showInformationMessage(localize.DataScience.exportDialogComplete().format(file), localize.DataScience.exportOpenQuestion()).then((str : string | undefined) => {
+                await this.fileSystem.writeFile(file, JSON.stringify(notebook), { encoding: 'utf8', flag: 'w' });
+                this.applicationShell.showInformationMessage(localize.DataScience.exportDialogComplete().format(file), localize.DataScience.exportOpenQuestion()).then((str: string | undefined) => {
                     if (str && this.jupyterServer) {
                         // If the user wants to, open the notebook they just generated.
                         this.jupyterExecution.spawnNotebook(file).ignoreErrors();
@@ -583,12 +586,12 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    private loadJupyterServer = async (restart?: boolean) : Promise<void> => {
+    private loadJupyterServer = async (restart?: boolean): Promise<void> => {
         // Startup our jupyter server
         const settings = this.configuration.getSettings();
         let serverURI: string | undefined = settings.datascience.jupyterServerURI;
         let workingDir: string | undefined;
-        const useDefaultConfig : boolean | undefined = settings.datascience.useDefaultConfigForJupyter;
+        const useDefaultConfig: boolean | undefined = settings.datascience.useDefaultConfigForJupyter;
         const status = this.setStatus(localize.DataScience.connectingToJupyter());
         try {
             // For the local case pass in our URI as undefined, that way connect doesn't have to check the setting
@@ -611,8 +614,7 @@ export class History implements IWebPanelMessageListener, IHistory {
     }
 
     // Calculate the working directory that we should move into when starting up our Jupyter server locally
-    private calculateWorkingDirectory = async (): Promise<string | undefined> =>
-    {
+    private calculateWorkingDirectory = async (): Promise<string | undefined> => {
         let workingDir: string | undefined;
         // For a local launch calculate the working directory that we should switch into
         const settings = this.configuration.getSettings();
@@ -631,21 +633,21 @@ export class History implements IWebPanelMessageListener, IHistory {
                     workingDir = workspaceFolderPath;
                 }
             } else {
-               // fileRoot is a relative path, combine it with the workspace folder
-               const combinedPath = path.join(workspaceFolderPath, fileRoot);
-               if (await this.fileSystem.directoryExists(combinedPath)) {
-                   // combined path exists, use it
-                   workingDir = combinedPath;
-               } else {
-                   // Combined path doesn't exist, use workspace
-                   workingDir = workspaceFolderPath;
-               }
+                // fileRoot is a relative path, combine it with the workspace folder
+                const combinedPath = path.join(workspaceFolderPath, fileRoot);
+                if (await this.fileSystem.directoryExists(combinedPath)) {
+                    // combined path exists, use it
+                    workingDir = combinedPath;
+                } else {
+                    // Combined path doesn't exist, use workspace
+                    workingDir = workspaceFolderPath;
+                }
             }
         }
         return workingDir;
     }
 
-    private extractStreamOutput(cell: ICell) : string {
+    private extractStreamOutput(cell: ICell): string {
         let result = '';
         if (cell.state === CellState.error || cell.state === CellState.finished) {
             const outputs = cell.data.outputs as nbformat.IOutput[];
@@ -666,7 +668,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         return result;
     }
 
-    private generateSysInfoCell = async (reason: SysInfoReason) : Promise<ICell | undefined> => {
+    private generateSysInfoCell = async (reason: SysInfoReason): Promise<ICell | undefined> => {
         // Execute the code 'import sys\r\nsys.version' and 'import sys\r\nsys.executable' to get our
         // version and executable
         if (this.jupyterServer) {
@@ -715,22 +717,22 @@ export class History implements IWebPanelMessageListener, IHistory {
     private async generateSysInfoMessage(reason: SysInfoReason): Promise<string> {
         switch (reason) {
             case SysInfoReason.Start:
-                    // Message depends upon if ipykernel is supported or not.
-                    if (!(await this.jupyterExecution.isKernelCreateSupported())) {
-                        return localize.DataScience.pythonVersionHeaderNoPyKernel();
-                    }
-                    return localize.DataScience.pythonVersionHeader();
-                    break;
+                // Message depends upon if ipykernel is supported or not.
+                if (!(await this.jupyterExecution.isKernelCreateSupported())) {
+                    return localize.DataScience.pythonVersionHeaderNoPyKernel();
+                }
+                return localize.DataScience.pythonVersionHeader();
+                break;
             case SysInfoReason.Restart:
-                    return localize.DataScience.pythonRestartHeader();
-                    break;
+                return localize.DataScience.pythonRestartHeader();
+                break;
             case SysInfoReason.Interrupt:
-                    return localize.DataScience.pythonInterruptFailedHeader();
-                    break;
+                return localize.DataScience.pythonInterruptFailedHeader();
+                break;
             default:
-                    this.logger.logError('Invalid SysInfoReason');
-                    return '';
-                    break;
+                this.logger.logError('Invalid SysInfoReason');
+                return '';
+                break;
         }
     }
 
@@ -745,7 +747,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         return `${localize.DataScience.sysInfoURILabel()}${urlString}`;
     }
 
-    private addSysInfo = async (reason: SysInfoReason) : Promise<void> => {
+    private addSysInfo = async (reason: SysInfoReason): Promise<void> => {
         if (!this.addedSysInfo || reason === SysInfoReason.Interrupt || reason === SysInfoReason.Restart) {
             this.addedSysInfo = true;
             this.ignoreCount = 0;
@@ -758,7 +760,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         }
     }
 
-    private loadWebPanel = async () : Promise<void> => {
+    private loadWebPanel = async (): Promise<void> => {
         // Create our web panel (it's the UI that shows up for the history)
 
         // Figure out the name of our main bundle. Should be in our output directory
@@ -772,7 +774,7 @@ export class History implements IWebPanelMessageListener, IHistory {
         this.webPanel = this.provider.create(this, localize.DataScience.historyTitle(), mainScriptPath, css);
     }
 
-    private load = async () : Promise<void> => {
+    private load = async (): Promise<void> => {
         const status = this.setStatus(localize.DataScience.startingJupyter());
 
         // Check to see if we support ipykernel or not
diff --git a/src/client/datascience/jupyter/jupyterExecution.ts b/src/client/datascience/jupyter/jupyterExecution.ts
index 7ebaa718d282..1ab69a4ed7e0 100644
--- a/src/client/datascience/jupyter/jupyterExecution.ts
+++ b/src/client/datascience/jupyter/jupyterExecution.ts
@@ -386,7 +386,9 @@ export class JupyterExecution implements IJupyterExecution, Disposable {
     private findSpecPath = async (specName: string, cancelToken?: CancellationToken): Promise<string | undefined> => {
         // Enumerate all specs and get path for the match
         const specs = await this.enumerateSpecs(cancelToken);
-        const match = specs.find(s => {
+        const match = specs!
+            .filter(s => s !== undefined)
+            .find(s => {
             const js = s as JupyterKernelSpec;
             return js && js.name === specName;
         }) as JupyterKernelSpec;
@@ -557,7 +559,7 @@ export class JupyterExecution implements IJupyterExecution, Disposable {
 
                     // Then let them run concurrently (they are file io)
                     const specs = await Promise.all(promises);
-                    return specs.filter(s => s);
+                    return specs!.filter(s => s);
                 } catch {
                     // This is failing for some folks. In that case return nothing
                     return [];
diff --git a/src/test/datascience/dataScienceIocContainer.ts b/src/test/datascience/dataScienceIocContainer.ts
index 7f189ddc8271..c9ebc6a796a5 100644
--- a/src/test/datascience/dataScienceIocContainer.ts
+++ b/src/test/datascience/dataScienceIocContainer.ts
@@ -152,7 +152,11 @@ import { MockJupyterManager } from './mockJupyterManager';
 
 export class DataScienceIocContainer extends UnitTestIocContainer {
 
-    private pythonSettings: PythonSettings = new PythonSettings(undefined, new MockAutoSelectionService());
+    private pythonSettings = new class extends PythonSettings {
+        public fireChangeEvent() {
+            this.changed.fire();
+        }
+    }(undefined, new MockAutoSelectionService());
     private commandManager: MockCommandManager = new MockCommandManager();
     private setContexts: { [name: string]: boolean } = {};
     private contextSetEvent: EventEmitter<{ name: string; value: boolean }> = new EventEmitter<{ name: string; value: boolean }>();
@@ -394,7 +398,7 @@ export class DataScienceIocContainer extends UnitTestIocContainer {
     }
 
     public forceSettingsChanged() {
-        this.pythonSettings.emit('change');
+        this.pythonSettings.fireChangeEvent();
     }
 
     public get mockJupyter(): MockJupyterManager | undefined {
diff --git a/src/test/datascience/mockJupyterManager.ts b/src/test/datascience/mockJupyterManager.ts
index dcde03799fc6..79c1e1d3a5c9 100644
--- a/src/test/datascience/mockJupyterManager.ts
+++ b/src/test/datascience/mockJupyterManager.ts
@@ -12,7 +12,6 @@ import { EventEmitter } from 'vscode';
 import { CancellationToken } from 'vscode-jsonrpc';
 
 import { Cancellation } from '../../client/common/cancellation';
-import { PythonSettings } from '../../client/common/configSettings';
 import { ExecutionResult, IProcessServiceFactory, IPythonExecutionFactory, Output } from '../../client/common/process/types';
 import { IAsyncDisposableRegistry, IConfigurationService } from '../../client/common/types';
 import { EXTENSION_ROOT_DIR } from '../../client/constants';
@@ -77,7 +76,7 @@ export class MockJupyterManager implements IJupyterSessionManager {
         // Listen to configuration changes like the real interpreter service does so that we fire our settings changed event
         const configService = serviceManager.get<IConfigurationService>(IConfigurationService);
         if (configService && configService !== null) {
-            (configService.getSettings() as PythonSettings).addListener('change', this.onConfigChanged);
+            configService.getSettings().onDidChange(this.onConfigChanged.bind(this));
         }
 
         // Stick our services into the service manager