diff --git a/src/dfmt-check.ts b/src/dfmt-check.ts
new file mode 100644
index 0000000..05fe6e7
--- /dev/null
+++ b/src/dfmt-check.ts
@@ -0,0 +1,40 @@
+import * as vscode from "vscode"
+
+function getMatchIndices(regex: RegExp, str: string) {
+	let result: number[] = [];
+	let match: RegExpExecArray;
+	while (match = regex.exec(str))
+		result.push(match.index);
+	return result;
+}
+
+let validDfmt = /\/\/dfmt (off|on)(\n|\s+|$)/;
+
+export function lintDfmt(doc: vscode.TextDocument, code: string) {
+	let locations = getMatchIndices(/\/\/dfmt/g, code);
+	let issues: vscode.Diagnostic[] = [];
+	let isOn: boolean = true;
+	locations.forEach(location => {
+		let part = code.substr(location, 11);
+		let match = validDfmt.exec(part);
+		if (!match) {
+			let pos = doc ? doc.positionAt(location) : new vscode.Position(0, 0);
+			issues.push(new vscode.Diagnostic(new vscode.Range(pos, pos.translate(0, 100)), "Not a valid dfmt command (try //dfmt off or //dfmt on instead)", vscode.DiagnosticSeverity.Warning));
+		} else {
+			if (match[1] == "off") {
+				if (!isOn) {
+					let pos = doc ? doc.positionAt(location) : new vscode.Position(0, 0);
+					issues.push(new vscode.Diagnostic(new vscode.Range(pos, pos.translate(0, 10)), "Redundant //dfmt off", vscode.DiagnosticSeverity.Information));
+				}
+				isOn = false;
+			} else {
+				if (isOn) {
+					let pos = doc ? doc.positionAt(location) : new vscode.Position(0, 0);
+					issues.push(new vscode.Diagnostic(new vscode.Range(pos, pos.translate(0, 9)), "Redundant //dfmt on", vscode.DiagnosticSeverity.Information));
+				}
+				isOn = true;
+			}
+		}
+	});
+	return issues;
+}
\ No newline at end of file
diff --git a/src/extension.ts b/src/extension.ts
index 4b99225..d258c44 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -6,6 +6,7 @@ import { uploadCode } from "./util"
 import * as statusbar from "./statusbar"
 import * as path from "path"
 import { DlangUIHandler } from "./dlangui"
+import { lintDfmt } from "./dfmt-check"
 
 let diagnosticCollection: vscode.DiagnosticCollection;
 
@@ -21,7 +22,7 @@ export function activate(context: vscode.ExtensionContext) {
 
 	let workspaced = new WorkspaceD(vscode.workspace.rootPath);
 	context.subscriptions.push(vscode.languages.registerCompletionItemProvider(DML_MODE, workspaced.getDlangUI()));
-	
+
 	context.subscriptions.push(vscode.languages.registerCompletionItemProvider(D_MODE, workspaced, "."));
 	context.subscriptions.push(vscode.languages.registerSignatureHelpProvider(D_MODE, workspaced, "(", ","));
 	context.subscriptions.push(vscode.languages.registerDocumentSymbolProvider(D_MODE, workspaced));
@@ -79,7 +80,7 @@ export function activate(context: vscode.ExtensionContext) {
 			decreaseIndentPattern: /\}/,
 			increaseIndentPattern: /\{/
 		},
-		
+
 		wordPattern: /[a-zA-Z_][a-zA-Z0-9_]*/g,
 
 		brackets: [
@@ -95,7 +96,34 @@ export function activate(context: vscode.ExtensionContext) {
 	context.subscriptions.push(diagnosticCollection);
 
 	let version;
-	let oldLint = [[], []];
+	let writeTimeout;
+	let oldLint: [vscode.Uri, vscode.Diagnostic[]][][] = [[], [], []];
+	context.subscriptions.push(vscode.workspace.onDidChangeTextDocument(event => {
+		clearTimeout(writeTimeout);
+		writeTimeout = setTimeout(function() {
+			let document = event.document;
+			if (document.languageId != "d")
+				return;
+			version = document.version;
+			let target = version;
+			if (config().get("enableLinting", true)) {
+				let allErrors: [vscode.Uri, vscode.Diagnostic[]][] = [];
+
+				let fresh = true;
+				let buildErrors = () => {
+					allErrors = [];
+					oldLint.forEach(errors => {
+						allErrors.push.apply(allErrors, errors);
+					});
+					diagnosticCollection.set(allErrors);
+				};
+
+				oldLint[2] = [[document.uri, lintDfmt(document, document.getText())]];
+				buildErrors();
+			}
+		}, 500);
+	}));
+
 	context.subscriptions.push(vscode.workspace.onDidSaveTextDocument(document => {
 		if (document.languageId != "d")
 			return;
@@ -113,6 +141,8 @@ export function activate(context: vscode.ExtensionContext) {
 				diagnosticCollection.set(allErrors);
 			};
 
+			oldLint[2] = [[document.uri, lintDfmt(document, document.getText())]];
+			buildErrors();
 			workspaced.lint(document).then((errors: [vscode.Uri, vscode.Diagnostic[]][]) => {
 				if (target == version) {
 					oldLint[0] = errors;
@@ -196,7 +226,7 @@ export function activate(context: vscode.ExtensionContext) {
 			vscode.window.showErrorMessage("Could not update imports. dub might not be initialized yet!");
 		});
 	}));
-	
+
 	context.subscriptions.push(vscode.commands.registerCommand("code-d.insertDscanner", () => {
 		vscode.window.activeTextEditor.edit((bld) => {
 			bld.insert(vscode.window.activeTextEditor.selection.start, `; Configurue which static analysis checks are enabled
diff --git a/test/dfmt-check.test.ts b/test/dfmt-check.test.ts
new file mode 100644
index 0000000..7559359
--- /dev/null
+++ b/test/dfmt-check.test.ts
@@ -0,0 +1,30 @@
+import * as assert from 'assert';
+import * as vscode from 'vscode';
+import { lintDfmt } from '../src/dfmt-check';
+
+// Defines a Mocha test suite to group tests of similar kind together
+suite("dfmt lint", () => {
+	test("misspelling on/off", () => {
+		let linted = lintDfmt(undefined, `void foo() {
+			//dfmt offs
+			int i = 5;
+			//dfmt onf
+		}`);
+		assert.strictEqual(linted.length, 2);
+		assert.strictEqual(linted[0].severity, vscode.DiagnosticSeverity.Warning);
+		assert.strictEqual(linted[1].severity, vscode.DiagnosticSeverity.Warning);
+	});
+	test("redundant on/off", () => {
+		let linted = lintDfmt(undefined, `void foo() {
+			//dfmt on
+			//dfmt off
+			int i = 5;
+			//dfmt off
+			//dfmt ons
+		}`);
+		assert.strictEqual(linted.length, 3);
+		assert.strictEqual(linted[0].severity, vscode.DiagnosticSeverity.Information);
+		assert.strictEqual(linted[1].severity, vscode.DiagnosticSeverity.Information);
+		assert.strictEqual(linted[2].severity, vscode.DiagnosticSeverity.Warning);
+	});
+});
\ No newline at end of file
diff --git a/test/extension.test.ts b/test/extension.test.ts
deleted file mode 100644
index 1cec6f4..0000000
--- a/test/extension.test.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-// 
-// Note: This example test is leveraging the Mocha test framework.
-// Please refer to their documentation on https://mochajs.org/ for help.
-//
-
-// The module 'assert' provides assertion methods from node
-import * as assert from 'assert';
-
-// You can import and use all API from the 'vscode' module
-// as well as import your extension to test it
-import * as vscode from 'vscode';
-import * as myExtension from '../src/extension';
-
-// Defines a Mocha test suite to group tests of similar kind together
-suite("Extension Tests", () => {
-
-	// Defines a Mocha unit test
-	test("Something 1", () => {
-		assert.equal(-1, [1, 2, 3].indexOf(5));
-		assert.equal(-1, [1, 2, 3].indexOf(0));
-	});
-});
\ No newline at end of file