diff --git a/src/internal/animations.js b/src/internal/animations.js
index b8ed7407ef..7e6b112fd0 100644
--- a/src/internal/animations.js
+++ b/src/internal/animations.js
@@ -1,4 +1,4 @@
-import { identity as linear } from './utils.js';
+import { identity as linear, noop } from './utils.js';
 import { loop } from './loop.js';
 import { create_rule, delete_rule } from './style_manager.js';
 
@@ -8,59 +8,50 @@ export function wrapAnimation(node, from, fn, params) {
 	const to = node.getBoundingClientRect();
 	if (from.left === to.left && from.right === to.right && from.top === to.top && from.bottom === to.bottom) return;
 
-	const info = fn(node, { from, to }, params);
+	const {
+		delay = 0,
+		duration = 300,
+		easing = linear,
+		start: start_time = window.performance.now() + delay,
+		end = start_time + duration,
+		tick = noop,
+		css
+	} = fn(node, { from, to }, params);
 
-	const duration = 'duration' in info ? info.duration : 300;
-	const delay = 'delay' in info ? info.delay : 0;
-	const ease = info.easing || linear;
-	const start_time = window.performance.now() + delay;
-	const end = start_time + duration;
-
-	const program = {
-		a: 0,
-		t: 0,
-		b: 1,
-		delta: 1,
-		duration,
-		start: start_time,
-		end
-	};
+	let running = true;
+	let started = false;
+	let name;
 
 	const cssText = node.style.cssText;
 
 	function start() {
-		if (info.css) {
+		if (css) {
 			if (delay) node.style.cssText = cssText;
 
-			program.name = create_rule(program, ease, info.css);
+			name = create_rule({ a: 0, b: 1, delta: 1, duration }, easing, css);
 
 			node.style.animation = (node.style.animation || '')
 				.split(', ')
-				.filter(anim => anim && (program.delta < 0 || !/__svelte/.test(anim)))
-				.concat(`${program.name} ${program.duration}ms linear 1 forwards`)
+				.filter(anim => anim && !/__svelte/.test(anim))
+				.concat(`${name} ${duration}ms linear 1 forwards`)
 				.join(', ');
 		}
 
-		running_program = program;
-		pending_program = null;
+		started = true;
 	}
 
-	let running = true;
-	let pending_program = delay ? program : null;
-	let running_program = delay ? null : program;
-
 	function stop() {
-		if (info.css) delete_rule(node, program.name);
+		if (css) delete_rule(node, name);
 		running = false;
 	}
 
 	const { abort, promise } = loop(now => {
-		if (pending_program && now >= pending_program.start) {
+		if (!started && now >= start_time) {
 			start();
 		}
 
-		if (running_program && now >= running_program.end) {
-			if (info.tick) info.tick(1, 0);
+		if (started && now >= end) {
+			tick(1, 0);
 			stop();
 		}
 
@@ -68,19 +59,19 @@ export function wrapAnimation(node, from, fn, params) {
 			return false;
 		}
 
-		if (running_program) {
-			const p = now - program.start;
-			const t = program.a + program.delta * ease(p / program.duration);
-			if (info.tick) info.tick(t, 1 - t);
+		if (started) {
+			const p = now - start_time;
+			const t = 0 + 1 * easing(p / duration);
+			tick(t, 1 - t);
 		}
 
 		return true;
 	});
 
-	if (info.tick) info.tick(0, 1);
+	tick(0, 1);
 
 	if (delay) {
-		if (info.css) node.style.cssText += info.css(0, 1);
+		if (css) node.style.cssText += css(0, 1);
 	} else {
 		start();
 	}