diff --git a/src/compiler/compile/render_dom/Renderer.ts b/src/compiler/compile/render_dom/Renderer.ts
index 9618a0d854..543d6b0066 100644
--- a/src/compiler/compile/render_dom/Renderer.ts
+++ b/src/compiler/compile/render_dom/Renderer.ts
@@ -138,11 +138,15 @@ export default class Renderer {
 			.reduce((lhs, rhs) => x`${lhs}, ${rhs}}`);
 	}
 
-	changed(names, needs_update = false) {
-		const bitmask = names.reduce((bits, name) => {
+	get_bitmask(names) {
+		return names.reduce((bits, name) => {
 			const bit = 1 << this.context_lookup.get(name);
 			return bits | bit;
 		}, 0);
+	}
+
+	changed(names, needs_update = false) {
+		const bitmask = this.get_bitmask(names);
 
 		return needs_update
 			? x`(#changed = $$self.$$.dirty) & ${bitmask}`
diff --git a/src/compiler/compile/render_dom/wrappers/InlineComponent/index.ts b/src/compiler/compile/render_dom/wrappers/InlineComponent/index.ts
index b4a2d13d53..155612e878 100644
--- a/src/compiler/compile/render_dom/wrappers/InlineComponent/index.ts
+++ b/src/compiler/compile/render_dom/wrappers/InlineComponent/index.ts
@@ -16,10 +16,41 @@ import is_dynamic from '../shared/is_dynamic';
 import bind_this from '../shared/bind_this';
 import { Node, Identifier, ObjectExpression } from 'estree';
 import EventHandler from '../Element/EventHandler';
+import Let from '../../../nodes/Let';
+
+function get_changes_merger(renderer: Renderer, lets: Let[]) {
+	if (lets.length === 0) return null;
+
+	const input = {
+		type: 'ObjectPattern',
+		properties: lets.map(l => ({
+			type: 'Property',
+			kind: 'init',
+			key: l.name,
+			value: l.value || l.name
+		}))
+	};
+
+	const names: Set<string> = new Set();
+	lets.forEach(l => {
+		l.names.forEach(name => {
+			names.add(name);
+		});
+	});
+
+	const expressions = Array.from(names).map(name => {
+		const i = renderer.context_lookup.get(name);
+		return x`${name} ? ${1 << i} : 0`;
+	});
+
+	const output = expressions.reduce((lhs, rhs) => x`${lhs} | ${rhs}`);
+
+	return x`(${input}) => (${output})`;
+}
 
 export default class InlineComponentWrapper extends Wrapper {
 	var: Identifier;
-	slots: Map<string, { block: Block; scope: TemplateScope; fn?: Node }> = new Map();
+	slots: Map<string, { block: Block; scope: TemplateScope; get_context?: Node, get_changes?: Node }> = new Map();
 	node: InlineComponent;
 	fragment: FragmentWrapper;
 
@@ -74,7 +105,7 @@ export default class InlineComponentWrapper extends Wrapper {
 
 		if (this.node.children.length) {
 			this.node.lets.forEach(l => {
-				renderer.add_to_context(l.value.name, true);
+				renderer.add_to_context((l.value || l.name).name, true);
 			});
 
 			const default_slot = block.child({
@@ -85,12 +116,11 @@ export default class InlineComponentWrapper extends Wrapper {
 
 			this.renderer.blocks.push(default_slot);
 
-			const fn = get_context_merger(this.renderer, this.node.lets);
-
 			this.slots.set('default', {
 				block: default_slot,
 				scope: this.node.scope,
-				fn
+				get_context: get_context_merger(this.renderer, this.node.lets),
+				get_changes: get_changes_merger(this.renderer, this.node.lets)
 			});
 			this.fragment = new FragmentWrapper(renderer, default_slot, node.children, this, strip_whitespace, next_sibling);
 
@@ -133,7 +163,7 @@ export default class InlineComponentWrapper extends Wrapper {
 			? [
 				p`$$slots: {
 					${Array.from(this.slots).map(([name, slot]) => {
-						return p`${name}: [${slot.block.name}, ${slot.fn || null}]`;
+						return p`${name}: [${slot.block.name}, ${slot.get_context || null}, ${slot.get_changes || null}]`;
 					})}
 				}`,
 				p`$$scope: {
diff --git a/src/compiler/compile/render_dom/wrappers/Slot.ts b/src/compiler/compile/render_dom/wrappers/Slot.ts
index 044eb04583..123b6776e8 100644
--- a/src/compiler/compile/render_dom/wrappers/Slot.ts
+++ b/src/compiler/compile/render_dom/wrappers/Slot.ts
@@ -90,16 +90,13 @@ export default class SlotWrapper extends Wrapper {
 				});
 
 				if (dynamic_dependencies.length > 0) {
-					const expression = dynamic_dependencies
-						.map(name => ({ type: 'Identifier', name } as any))
-						.reduce((lhs, rhs) => x`${lhs} || ${rhs}`);
-
-					changes.properties.push(p`${attribute.name}: ${expression}`);
+					const bitmask = renderer.get_bitmask(dynamic_dependencies);
+					changes.properties.push(p`${attribute.name}: #changes & ${bitmask}`);
 				}
 			});
 
 			renderer.blocks.push(b`
-				const ${get_slot_changes_fn} = #changes => #changes;
+				const ${get_slot_changes_fn} = #changes => ${changes};
 				const ${get_slot_context_fn} = #ctx => ${get_slot_data(block, this.node.values)};
 			`);
 		} else {
diff --git a/src/runtime/internal/utils.ts b/src/runtime/internal/utils.ts
index fab44f80db..97b83f360f 100644
--- a/src/runtime/internal/utils.ts
+++ b/src/runtime/internal/utils.ts
@@ -77,8 +77,8 @@ export function get_slot_context(definition, ctx, $$scope, fn) {
 }
 
 export function get_slot_changes(definition, $$scope, changed, fn) {
-	return definition[1] && fn
-		? $$scope.changed | definition[1](fn(changed))
+	return definition[2] && fn
+		? $$scope.changed | definition[2](fn(changed))
 		: $$scope.changed;
 }