diff --git a/typed-html/src/events.rs b/typed-html/src/events.rs
index b543c93..038619d 100644
--- a/typed-html/src/events.rs
+++ b/typed-html/src/events.rs
@@ -6,7 +6,7 @@ use std::fmt::{Display, Error, Formatter};
 use std::iter;
 
 /// Trait for event handlers.
-pub trait EventHandler<T: OutputType, E> {
+pub trait EventHandler<T: OutputType + Send, E: Send> {
     /// Build a callback function from this event handler.
     ///
     /// Returns `None` is this event handler can't be used to build a callback
@@ -26,13 +26,13 @@ pub trait EventHandler<T: OutputType, E> {
 
 macro_rules! declare_events_struct {
     ($($name:ident,)*) => {
-        pub struct Events<T> {
+        pub struct Events<T> where T: Send {
             $(
                 pub $name: Option<T>,
             )*
         }
 
-        impl<T> Events<T> {
+        impl<T: Send> Events<T> {
             pub fn iter(&self) -> impl Iterator<Item = (&'static str, &T)> {
                 iter::empty()
                 $(
@@ -54,7 +54,7 @@ macro_rules! declare_events_struct {
             }
         }
 
-        impl<T: 'static> IntoIterator for Events<T> {
+        impl<T: 'static + Send> IntoIterator for Events<T> {
             type Item = (&'static str, T);
             type IntoIter = Box<dyn Iterator<Item = Self::Item>>;
 
@@ -72,7 +72,7 @@ macro_rules! declare_events_struct {
             }
         }
 
-        impl<T> Default for Events<T> {
+        impl<T: Send> Default for Events<T> {
             fn default() -> Self {
                 Events {
                     $(
@@ -82,7 +82,7 @@ macro_rules! declare_events_struct {
             }
         }
 
-        impl<T: Display> Display for Events<T> {
+        impl<T: Display + Send> Display for Events<T> {
             fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
                 $(
                     if let Some(ref value) = self.$name {
diff --git a/typed-html/src/lib.rs b/typed-html/src/lib.rs
index ef53afe..de9a23b 100644
--- a/typed-html/src/lib.rs
+++ b/typed-html/src/lib.rs
@@ -214,11 +214,11 @@ pub mod types;
 /// Marker trait for outputs
 pub trait OutputType {
     /// The type that contains events for this output.
-    type Events: Default + Display;
+    type Events: Default + Display + Send;
     /// The type of event targets for this output.
-    type EventTarget;
+    type EventTarget: Send;
     /// The type that's returned from attaching an event listener to a target.
-    type EventListenerHandle;
+    type EventListenerHandle: Send;
 }
 
 /// String output
diff --git a/typed-html/src/output/stdweb.rs b/typed-html/src/output/stdweb.rs
index b2cc884..d96baf6 100644
--- a/typed-html/src/output/stdweb.rs
+++ b/typed-html/src/output/stdweb.rs
@@ -21,7 +21,7 @@ macro_rules! declare_events {
         /// Container type for DOM events.
         pub struct Events {
             $(
-                pub $name: Option<Box<dyn EventHandler<Stdweb, $type>>>,
+                pub $name: Option<Box<dyn EventHandler<Stdweb, $type> + Send>>,
             )*
         }
 
@@ -129,17 +129,17 @@ pub struct EFn<F, E>(Option<F>, PhantomData<E>);
 
 impl<F, E> EFn<F, E>
 where
-    F: FnMut(E) + 'static,
+    F: FnMut(E) + 'static + Send,
 {
     pub fn new(f: F) -> Self {
         EFn(Some(f), PhantomData)
     }
 }
 
-impl<F, E> From<F> for Box<dyn EventHandler<Stdweb, E>>
+impl<F, E> From<F> for Box<dyn EventHandler<Stdweb, E> + Send>
 where
-    F: FnMut(E) + 'static,
-    E: ConcreteEvent + 'static,
+    F: FnMut(E) + 'static + Send,
+    E: ConcreteEvent + 'static + Send,
 {
     fn from(f: F) -> Self {
         Box::new(EFn::new(f))
@@ -148,8 +148,8 @@ where
 
 impl<F, E> EventHandler<Stdweb, E> for EFn<F, E>
 where
-    F: FnMut(E) + 'static,
-    E: ConcreteEvent + 'static,
+    F: FnMut(E) + 'static + Send,
+    E: ConcreteEvent + 'static + Send,
 {
     fn attach(&mut self, target: &mut <Stdweb as OutputType>::EventTarget) -> EventListenerHandle {
         let handler = self.0.take().unwrap();