diff --git a/src/compiler/compile/render_dom/index.ts b/src/compiler/compile/render_dom/index.ts
index c1c2ebae56..b41b4c2f08 100644
--- a/src/compiler/compile/render_dom/index.ts
+++ b/src/compiler/compile/render_dom/index.ts
@@ -75,6 +75,7 @@ export default function dom(
 	const $$props = uses_props ? `$$new_props` : `$$props`;
 	const props = component.vars.filter(variable => !variable.module && variable.export_name);
 	const writable_props = props.filter(variable => variable.writable);
+	const writable_vars = component.vars.filter(variable => !variable.module && variable.writable);
 
 	/* eslint-disable @typescript-eslint/indent,indent */
 	const set = (uses_props || writable_props.length > 0 || component.slots.size > 0)
@@ -89,6 +90,16 @@ export default function dom(
 			}
 		`
 		: null;
+
+	const unsafe_set = writable_vars.length > 0
+		? deindent`
+			$$values => {
+				${writable_vars.map(variable =>
+					`if ('${variable.name}' in $$values) ${component.invalidate(variable.name, `${variable.name} = $$values.${variable.name}`)};`
+				)}
+			}
+		`
+		: null;
 	/* eslint-enable @typescript-eslint/indent,indent */
 
 	const body = [];
@@ -430,6 +441,8 @@ export default function dom(
 
 				${set && `$$self.$set = ${set};`}
 
+				${unsafe_set && component.compile_options.dev && `$$self.$unsafe_set = ${unsafe_set};`}
+
 				${injected.length && `let ${injected.join(', ')};`}
 
 				${reactive_declarations.length > 0 && deindent`