diff --git a/src/compile/render-dom/index.ts b/src/compile/render-dom/index.ts
index afc6985c47..16a9f8f5d7 100644
--- a/src/compile/render-dom/index.ts
+++ b/src/compile/render-dom/index.ts
@@ -145,33 +145,10 @@ export default function dom(
 			`
 			: `@noop`;
 
-		const body = [
-			deindent`
-				$$init($$make_dirty) {
-					${component.init_uses_self && `const $$self = this;`}
-
-					${should_add_css &&
-					`if (!document.getElementById("${component.stylesheet.id}-style")) @add_css();`}
-
-					${component.javascript || component.exports.map(x => `let ${x.name};`)}
-
-					${component.partly_hoisted.length > 0 && component.partly_hoisted.join('\n\n')}
-
-					return [
-						// TODO only what's needed by the template
-						() => ({ ${component.declarations.join(', ')} }),
-						${inject_props},
-						${inject_refs}
-					];
-				}
-
-				$$create_fragment(${component.alias('component')}, ctx) {
-					${block.getContents()}
-				}
-			`
-		];
+		const body = [];
 
 		const debug_name = `<${component.customElement ? component.tag : name}>`;
+		const not_equal = component.options.immutable ? `@not_equal` : `@safe_not_equal`;
 
 		if (component.options.dev) {
 			// TODO check no uunexpected props were passed, as well as
@@ -219,11 +196,35 @@ export default function dom(
 		});
 
 		builder.addBlock(deindent`
+			function $$create_fragment(${component.alias('component')}, ctx) {
+				${block.getContents()}
+			}
+
 			${component.module_javascript}
 
 			${component.fully_hoisted.length > 0 && component.fully_hoisted.join('\n\n')}
 
+			function $$init($$self, $$make_dirty) {
+				${should_add_css &&
+				`if (!document.getElementById("${component.stylesheet.id}-style")) @add_css();`}
+
+				${component.javascript || component.exports.map(x => `let ${x.name};`)}
+
+				${component.partly_hoisted.length > 0 && component.partly_hoisted.join('\n\n')}
+
+				return [
+					// TODO only what's needed by the template
+					() => ({ ${component.declarations.join(', ')} }),
+					${inject_props},
+					${inject_refs}
+				];
+			}
+
 			class ${name} extends ${superclass} {
+				constructor(options) {
+					super(options, $$init, $$create_fragment, ${not_equal});
+				}
+
 				${body.join('\n\n')}
 			}
 		`);
diff --git a/src/internal/Component.js b/src/internal/Component.js
index 0cbd4d3226..9107276e16 100644
--- a/src/internal/Component.js
+++ b/src/internal/Component.js
@@ -5,7 +5,7 @@ import { blankObject } from './utils.js';
 import { children } from './dom.js';
 
 export class $$Component {
-	constructor(options) {
+	constructor(options, init, create_fragment, not_equal) {
 		this.$$beforeRender = [];
 		this.$$onMount = [];
 		this.$$afterRender = [];
@@ -16,14 +16,15 @@ export class $$Component {
 		this.$$slotted = options.slots || {};
 
 		set_current_component(this);
-		const [get_state, inject_props, inject_refs] = this.$$init(
+		const [get_state, inject_props, inject_refs] = init(
+			this,
 			key => {
 				this.$$make_dirty(key);
 				if (this.$$bindings[key]) this.$$bindings[key](get_state()[key]);
 			}
 		);
 
-		this.$$ = { get_state, inject_props, inject_refs };
+		this.$$ = { get_state, inject_props, inject_refs, not_equal };
 
 		this.$$refs = {};
 
@@ -35,7 +36,7 @@ export class $$Component {
 		}
 
 		run_all(this.$$beforeRender);
-		this.$$fragment = this.$$create_fragment(this, this.$$.get_state());
+		this.$$fragment = create_fragment(this, this.$$.get_state());
 
 		if (options.target) {
 			intro.enabled = !!options.intro;
@@ -63,8 +64,11 @@ export class $$Component {
 
 	$set(values) {
 		if (this.$$) {
+			const state = this.$$.get_state();
 			this.$$.inject_props(values);
-			for (const key in values) this.$$make_dirty(key);
+			for (const key in values) {
+				if (this.$$.not_equal(state[key], values[key])) this.$$make_dirty(key);
+			}
 		}
 	}
 
@@ -137,7 +141,7 @@ export class $$ComponentDev extends $$Component {
 			throw new Error(`'target' is a required option`);
 		}
 
-		super(options);
+		super(...arguments);
 		this.$$checkProps();
 	}
 
diff --git a/src/internal/utils.js b/src/internal/utils.js
index 8443e1f7de..d50d2b3385 100644
--- a/src/internal/utils.js
+++ b/src/internal/utils.js
@@ -47,4 +47,12 @@ export function run_all(fns) {
 
 export function is_function(thing) {
 	return typeof thing === 'function';
+}
+
+export function safe_not_equal(a, b) {
+	return a != a ? b == b : a !== b || ((a && typeof a === 'object') || typeof a === 'function');
+}
+
+export function not_equal(a, b) {
+	return a != a ? b == b : a !== b;
 }
\ No newline at end of file