diff --git a/core/src/nodes/collection.rs b/core/src/nodes/collection.rs
index 347a8c9a..eb346092 100644
--- a/core/src/nodes/collection.rs
+++ b/core/src/nodes/collection.rs
@@ -309,7 +309,7 @@ where
 {
     /// Creates a new empty collection. If `executor` is `Some`, uses the given executor to spawn
     /// tasks. Otherwise, runs tasks locally.
-    pub fn new(executor: Option<Box<dyn Executor>>) -> Self {
+    pub fn new(executor: Option<Box<dyn Executor + Send>>) -> Self {
         CollectionStream {
             inner: tasks::Manager::new(executor),
             nodes: Default::default(),
diff --git a/core/src/nodes/network.rs b/core/src/nodes/network.rs
index 16594c27..c6059209 100644
--- a/core/src/nodes/network.rs
+++ b/core/src/nodes/network.rs
@@ -688,7 +688,7 @@ where
     TPeerId: Eq + Hash + Clone,
 {
     /// Creates a new node events stream.
-    pub fn new(transport: TTrans, local_peer_id: TPeerId, executor: Option<Box<dyn Executor>>) -> Self {
+    pub fn new(transport: TTrans, local_peer_id: TPeerId, executor: Option<Box<dyn Executor + Send>>) -> Self {
         // TODO: with_capacity?
         Network {
             listeners: ListenersStream::new(transport),
@@ -706,7 +706,7 @@ where
 
     /// Creates a new node event stream with incoming connections limit.
     pub fn new_with_incoming_limit(transport: TTrans,
-        local_peer_id: TPeerId, executor: Option<Box<dyn Executor>>, incoming_limit: Option<u32>) -> Self
+        local_peer_id: TPeerId, executor: Option<Box<dyn Executor + Send>>, incoming_limit: Option<u32>) -> Self
     {
         Network {
             incoming_limit,
diff --git a/core/src/nodes/tasks/manager.rs b/core/src/nodes/tasks/manager.rs
index ad891c4a..47c0a63c 100644
--- a/core/src/nodes/tasks/manager.rs
+++ b/core/src/nodes/tasks/manager.rs
@@ -65,7 +65,7 @@ pub struct Manager<I, O, H, E, HE, T, C = PeerId> {
 
     /// Custom executor where we spawn the nodes' tasks. If `None`, then we push tasks to the
     /// `local_spawns` list instead.
-    executor: Option<Box<dyn Executor>>,
+    executor: Option<Box<dyn Executor + Send>>,
 
     /// If no executor is available, we move tasks to this set, and futures are polled on the
     /// current thread instead.
@@ -136,7 +136,7 @@ pub enum Event<'a, I, O, H, E, HE, T, C = PeerId> {
 impl<I, O, H, E, HE, T, C> Manager<I, O, H, E, HE, T, C> {
     /// Creates a new task manager. If `Some` is passed, uses the given executor to spawn tasks.
     /// Otherwise, background tasks are executed locally when you call `poll`.
-    pub fn new(executor: Option<Box<dyn Executor>>) -> Self {
+    pub fn new(executor: Option<Box<dyn Executor + Send>>) -> Self {
         let (tx, rx) = mpsc::channel(1);
         Self {
             tasks: FnvHashMap::default(),
diff --git a/swarm/src/lib.rs b/swarm/src/lib.rs
index 3a02aa91..09a1c7f4 100644
--- a/swarm/src/lib.rs
+++ b/swarm/src/lib.rs
@@ -572,7 +572,7 @@ impl<'a> PollParameters for SwarmPollParameters<'a> {
 
 pub struct SwarmBuilder<TTransport, TBehaviour> {
     incoming_limit: Option<u32>,
-    executor: Option<Box<dyn Executor>>,
+    executor: Option<Box<dyn Executor + Send>>,
     local_peer_id: PeerId,
     transport: TTransport,
     behaviour: TBehaviour,
@@ -626,13 +626,13 @@ where TBehaviour: NetworkBehaviour,
     /// Sets the executor to use to spawn background tasks.
     ///
     /// By default, uses a threads pool.
-    pub fn executor(mut self, executor: impl Executor + 'static) -> Self {
+    pub fn executor(mut self, executor: impl Executor + Send + 'static) -> Self {
         self.executor = Some(Box::new(executor));
         self
     }
 
     /// Shortcut for calling `executor` with an object that calls the given closure.
-    pub fn executor_fn(mut self, executor: impl Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + 'static) -> Self {
+    pub fn executor_fn(mut self, executor: impl Fn(Pin<Box<dyn Future<Output = ()> + Send>>) + Send + 'static) -> Self {
         struct SpawnImpl<F>(F);
         impl<F: Fn(Pin<Box<dyn Future<Output = ()> + Send>>)> Executor for SpawnImpl<F> {
             fn exec(&self, f: Pin<Box<dyn Future<Output = ()> + Send>>) {