diff --git a/src/ConfigurationManager.ts b/src/ConfigurationManager.ts
index fdd63adf..02962679 100644
--- a/src/ConfigurationManager.ts
+++ b/src/ConfigurationManager.ts
@@ -31,7 +31,7 @@ import {
   workspace,
   WorkspaceConfiguration,
 } from "vscode";
-import * as Constants from "./Constants";
+import * as Constants from "./Constants.js";
 
 export class ConfigurationManager implements Disposable {
   // Private Members
diff --git a/src/FormattingProviderDashes.ts b/src/FormattingProviderDashes.ts
index 86d615b4..b6a80d7d 100644
--- a/src/FormattingProviderDashes.ts
+++ b/src/FormattingProviderDashes.ts
@@ -15,10 +15,11 @@
  */
 
 import * as vscode from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
+import { ConfigurationManager } from "./ConfigurationManager.js";
 
 export class FormattingProviderDashes
-  implements vscode.OnTypeFormattingEditProvider {
+  implements vscode.OnTypeFormattingEditProvider
+{
   public static readonly emDash: string = "—";
   public static readonly enDash: string = "–";
   public static readonly hyphen: string = "-";
diff --git a/src/FormattingProviderEllipses.ts b/src/FormattingProviderEllipses.ts
index 11e0e9d9..cd1ba577 100644
--- a/src/FormattingProviderEllipses.ts
+++ b/src/FormattingProviderEllipses.ts
@@ -15,10 +15,11 @@
  */
 
 import * as vscode from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
+import { ConfigurationManager } from "./ConfigurationManager.js";
 
 export class FormattingProviderEllipses
-  implements vscode.OnTypeFormattingEditProvider {
+  implements vscode.OnTypeFormattingEditProvider
+{
   public static readonly ellipses: string = "…";
   public static readonly period: string = ".";
   public static readonly triggers: string[] = ["."];
diff --git a/src/FormattingProviderQuotes.ts b/src/FormattingProviderQuotes.ts
index 7bd9d3f3..0c7b66ad 100644
--- a/src/FormattingProviderQuotes.ts
+++ b/src/FormattingProviderQuotes.ts
@@ -15,10 +15,11 @@
  */
 
 import * as vscode from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
+import { ConfigurationManager } from "./ConfigurationManager.js";
 
 export class FormattingProviderQuotes
-  implements vscode.OnTypeFormattingEditProvider {
+  implements vscode.OnTypeFormattingEditProvider
+{
   public static readonly startDoubleQuote: string = "“";
   public static readonly endDoubleQuote: string = "”";
   public static readonly startSingleQuote: string = "‘";
diff --git a/src/Linter.ts b/src/Linter.ts
index 3e09b002..4e990bb0 100644
--- a/src/Linter.ts
+++ b/src/Linter.ts
@@ -37,18 +37,18 @@ import {
   workspace,
   WorkspaceEdit,
 } from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
-import * as Constants from "./Constants";
-import { FormattingProviderDashes } from "./FormattingProviderDashes";
-import { FormattingProviderEllipses } from "./FormattingProviderEllipses";
-import { FormattingProviderQuotes } from "./FormattingProviderQuotes";
+import { ConfigurationManager } from "./ConfigurationManager.js";
+import * as Constants from "./Constants.js";
+import { FormattingProviderDashes } from "./FormattingProviderDashes.js";
+import { FormattingProviderEllipses } from "./FormattingProviderEllipses.js";
+import { FormattingProviderQuotes } from "./FormattingProviderQuotes.js";
 import {
   IIgnoreItem,
   ILanguageToolMatch,
   ILanguageToolReplacement,
   ILanguageToolResponse,
-} from "./Interfaces";
-import { StatusBarManager } from "./StatusBarManager";
+} from "./Interfaces.js";
+import { StatusBarManager } from "./StatusBarManager.js";
 
 class LTDiagnostic extends Diagnostic {
   match?: ILanguageToolMatch;
diff --git a/src/StatusBarManager.ts b/src/StatusBarManager.ts
index 3c6d8b5a..405993f7 100644
--- a/src/StatusBarManager.ts
+++ b/src/StatusBarManager.ts
@@ -14,8 +14,8 @@
  *   limitations under the License.
  */
 import * as vscode from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
-import { ILanguageToolResponse } from "./Interfaces";
+import { ConfigurationManager } from "./ConfigurationManager.js";
+import { ILanguageToolResponse } from "./Interfaces.js";
 
 export class StatusBarManager implements vscode.Disposable {
   private statusBarItem: vscode.StatusBarItem;
diff --git a/src/extension.ts b/src/extension.ts
index 69c7b108..514cd493 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -16,13 +16,13 @@
 
 import { IAnnotatedtext } from "annotatedtext";
 import * as vscode from "vscode";
-import { ConfigurationManager } from "./ConfigurationManager";
-import * as Constants from "./Constants";
-import { FormattingProviderDashes } from "./FormattingProviderDashes";
-import { FormattingProviderEllipses } from "./FormattingProviderEllipses";
-import { FormattingProviderQuotes } from "./FormattingProviderQuotes";
-import { Linter } from "./Linter";
-import { OnTypeFormattingDispatcher } from "./OnTypeFormattingDispatcher";
+import { ConfigurationManager } from "./ConfigurationManager.js";
+import * as Constants from "./Constants.js";
+import { FormattingProviderDashes } from "./FormattingProviderDashes.js";
+import { FormattingProviderEllipses } from "./FormattingProviderEllipses.js";
+import { FormattingProviderQuotes } from "./FormattingProviderQuotes.js";
+import { Linter } from "./Linter.js";
+import { OnTypeFormattingDispatcher } from "./OnTypeFormattingDispatcher.js";
 
 // Wonder Twin Powers, Activate!
 export function activate(context: vscode.ExtensionContext): void {
diff --git a/test/suite/configuration.test.ts b/test/suite/configuration.test.ts
index 06189e8f..8e5415fe 100644
--- a/test/suite/configuration.test.ts
+++ b/test/suite/configuration.test.ts
@@ -1,7 +1,7 @@
 import * as assert from "assert";
 import * as vscode from "vscode";
-import * as Constants from "../../src/Constants";
-import { ConfigurationManager } from "../../src/ConfigurationManager";
+import * as Constants from "../../src/Constants.js";
+import { ConfigurationManager } from "../../src/ConfigurationManager.js";
 
 suite("ConfigurationManager Test Suite", () => {
   test("ConfigurationManager should load configuration", () => {
diff --git a/test/suite/extension.test.ts b/test/suite/extension.test.ts
index 4c287be9..564f7827 100644
--- a/test/suite/extension.test.ts
+++ b/test/suite/extension.test.ts
@@ -2,7 +2,7 @@ import * as assert from "assert";
 // tslint:disable-next-line: no-implicit-dependencies
 import { before } from "mocha";
 import * as vscode from "vscode";
-import * as Constants from "../../src/Constants";
+import * as Constants from "../../src/Constants.js";
 
 suite("Extension Test Suite", () => {
   before(() => {
diff --git a/test/suite/linter.html.test.ts b/test/suite/linter.html.test.ts
index 3e519f09..d7f1d413 100644
--- a/test/suite/linter.html.test.ts
+++ b/test/suite/linter.html.test.ts
@@ -1,9 +1,9 @@
 import * as assert from "assert";
 import * as fs from "fs";
 import * as path from "path";
-import { ConfigurationManager } from "../../src/ConfigurationManager";
+import { ConfigurationManager } from "../../src/ConfigurationManager.js";
 import { IAnnotatedtext } from "annotatedtext";
-import { Linter } from "../../src/Linter";
+import { Linter } from "../../src/Linter.js";
 
 suite("Linter HTML Test Suite", () => {
   const configManager: ConfigurationManager = new ConfigurationManager();
diff --git a/test/suite/linter.markdown.test.ts b/test/suite/linter.markdown.test.ts
index d1e7ad41..7cb4736e 100644
--- a/test/suite/linter.markdown.test.ts
+++ b/test/suite/linter.markdown.test.ts
@@ -1,8 +1,8 @@
 import * as assert from "assert";
 import * as fs from "fs";
 import * as path from "path";
-import { ConfigurationManager } from "../../src/ConfigurationManager";
-import { Linter } from "../../src/Linter";
+import { ConfigurationManager } from "../../src/ConfigurationManager.js";
+import { Linter } from "../../src/Linter.js";
 
 suite("Linter Markdown Test Suite", () => {
   const configManager: ConfigurationManager = new ConfigurationManager();
diff --git a/test/suite/linter.mdx.test.ts b/test/suite/linter.mdx.test.ts
index b27b8b65..db96354d 100644
--- a/test/suite/linter.mdx.test.ts
+++ b/test/suite/linter.mdx.test.ts
@@ -1,8 +1,8 @@
 import * as assert from "assert";
 import * as fs from "fs";
 import * as path from "path";
-import { ConfigurationManager } from "../../src/ConfigurationManager";
-import { Linter } from "../../src/Linter";
+import { ConfigurationManager } from "../../src/ConfigurationManager.js";
+import { Linter } from "../../src/Linter.js";
 
 suite("Linter MDX Test Suite", () => {
   const configManager: ConfigurationManager = new ConfigurationManager();
diff --git a/test/suite/linter.test.ts b/test/suite/linter.test.ts
index 0af2d4e3..49f52dcd 100644
--- a/test/suite/linter.test.ts
+++ b/test/suite/linter.test.ts
@@ -1,9 +1,9 @@
 import * as assert from "assert";
 import * as fs from "fs";
 import * as path from "path";
-import { ConfigurationManager } from "../../src/ConfigurationManager";
+import { ConfigurationManager } from "../../src/ConfigurationManager.js";
 import { IAnnotatedtext } from "annotatedtext";
-import { Linter } from "../../src/Linter";
+import { Linter } from "../../src/Linter.js";
 
 suite("Linter Test Suite", () => {
   const configManager: ConfigurationManager = new ConfigurationManager();