diff --git a/src/generators/dom/visitors/Element/addTransitions.js b/src/generators/dom/visitors/Element/addTransitions.js
index d053d89edb..526a9df6cc 100644
--- a/src/generators/dom/visitors/Element/addTransitions.js
+++ b/src/generators/dom/visitors/Element/addTransitions.js
@@ -31,18 +31,23 @@ export default function addTransitions ( generator, block, state, node, intro, o
 	}
 
 	else {
+		const introName = intro && block.getUniqueName( `${state.name}_intro` );
+		const outroName = outro && block.getUniqueName( `${state.name}_outro` );
+
 		if ( intro ) {
-			const name = block.getUniqueName( `${state.name}_intro` );
+			block.addVariable( introName );
 			const snippet = intro.expression ? block.contextualise( intro.expression ).snippet : '{}';
 
-			block.addVariable( name );
-
 			const fn = `${generator.alias( 'template' )}.transitions.${intro.name}`; // TODO add built-in transitions?
 
+			if ( outro ) {
+				block.builders.intro.addBlock( `if ( ${outroName} ) ${outroName}.abort();` );
+			}
+
 			block.builders.intro.addBlock( deindent`
 				${block.component}._renderHooks.push( function () {
-					${name} = ${wrapTransition}( ${state.name}, ${fn}, ${snippet}, true, null );
-					${name}.run( 0, 1, function () {
+					${introName} = ${wrapTransition}( ${state.name}, ${fn}, ${snippet}, true, null );
+					${introName}.run( 0, 1, function () {
 						${block.component}.fire( 'intro.end', { node: ${state.name} });
 					});
 				});
@@ -50,16 +55,14 @@ export default function addTransitions ( generator, block, state, node, intro, o
 		}
 
 		if ( outro ) {
-			const name = block.getUniqueName( `${state.name}_intro` );
+			block.addVariable( outroName );
 			const snippet = outro.expression ? block.contextualise( outro.expression ).snippet : '{}';
 
-			block.addVariable( name );
-
 			const fn = `${generator.alias( 'template' )}.transitions.${outro.name}`;
 
 			block.builders.outro.addBlock( deindent`
-				${name} = ${wrapTransition}( ${state.name}, ${fn}, ${snippet}, false, null );
-				${name}.run( 1, 0, function () {
+				${outroName} = ${wrapTransition}( ${state.name}, ${fn}, ${snippet}, false, null );
+				${outroName}.run( 1, 0, function () {
 					detachNode( ${state.name} );
 					${block.component}.fire( 'outro.end', { node: ${state.name} });
 					if ( --${block.alias( 'outros' )} === 0 ) ${block.alias( 'outrocallback' )}();
diff --git a/src/generators/dom/visitors/IfBlock.js b/src/generators/dom/visitors/IfBlock.js
index c4f1a435f8..00ddd049e3 100644
--- a/src/generators/dom/visitors/IfBlock.js
+++ b/src/generators/dom/visitors/IfBlock.js
@@ -89,6 +89,7 @@ function simple ( generator, block, state, node, branch, dynamic, { name, anchor
 	const exit = branch.hasOutroTransitions ?
 		deindent`
 			${name}.outro( function () {
+				${name}.destroy( true );
 				${name} = null;
 			});
 		` :
diff --git a/src/shared/transitions.js b/src/shared/transitions.js
index 65a3b23ff3..ddf3c55b3b 100644
--- a/src/shared/transitions.js
+++ b/src/shared/transitions.js
@@ -64,17 +64,16 @@ export function wrapTransition ( node, fn, params, intro, outgroup ) {
 	var style = document.createElement( 'style' );
 
 	var cleanup = function () {
-		if ( !transition.running ) return;
 		document.head.removeChild( style );
 		transition.running = false;
 	};
 
 	return assign( transition, {
 		generateKeyframes: function () {
-			id = 'svelte_' + ~~( Math.random() * 1e9 ); // TODO make this more robust
+			id = '__svelte' + ~~( Math.random() * 1e9 ); // TODO make this more robust
 			var keyframes = '@keyframes ' + id + '{\n';
 
-			for ( var p = 0; p <= 1; p += 166.666 / this.duration ) {
+			for ( var p = 0; p <= 1; p += 16.666 / this.duration ) {
 				var t = this.a + this.d * ease( p );
 				var styles = obj.styles( ease( t ) );
 				keyframes += ( p * 100 ) + '%{' + styles + '}\n';
@@ -85,7 +84,14 @@ export function wrapTransition ( node, fn, params, intro, outgroup ) {
 			style.textContent += keyframes;
 			document.head.appendChild( style );
 
-			node.style.animation += ( node.style.animation ? ', ' : '' ) + id + ' ' + this.duration + 'ms linear 1 forwards';
+			var d = this.d;
+			node.style.animation = node.style.animation.split( ',' )
+				.filter( function ( anim ) {
+					// when introing, discard old animations if there are any
+					return anim && ( d < 0 || !/__svelte/.test( anim ) );
+				})
+				.concat( id + ' ' + this.duration + 'ms linear 1 forwards' )
+				.join( ', ' );
 		},
 		update: function ( now ) {
 			const p = now - this.start;