diff --git a/core/src/runtime.rs b/core/src/runtime.rs
index 8dbe1440..f942ecff 100644
--- a/core/src/runtime.rs
+++ b/core/src/runtime.rs
@@ -5,6 +5,13 @@ pub(crate) mod raw;
 mod base;
 pub use base::{Runtime, WeakRuntime};
 
+/// The type of the interrupt handler.
+#[cfg(not(feature = "parallel"))]
+pub type InterruptHandler = Box<dyn FnMut() -> bool + 'static>;
+/// The type of the interrupt handler.
+#[cfg(feature = "parallel")]
+pub type InterruptHandler = Box<dyn FnMut() -> bool + Send + 'static>;
+
 #[cfg(feature = "futures")]
 mod r#async;
 #[cfg(feature = "futures")]
diff --git a/core/src/runtime/async.rs b/core/src/runtime/async.rs
index 18060e18..46249e7e 100644
--- a/core/src/runtime/async.rs
+++ b/core/src/runtime/async.rs
@@ -11,12 +11,15 @@ use async_lock::Mutex;
 use crate::allocator::Allocator;
 #[cfg(feature = "loader")]
 use crate::loader::{RawLoader, Resolver};
-use crate::{context::AsyncContext, result::AsyncJobException, Ctx, Error, Exception, Result};
+use crate::{
+    context::AsyncContext, markers::ParallelSend, result::AsyncJobException, Ctx, Error, Exception,
+    Result,
+};
 
 use super::{
     raw::{Opaque, RawRuntime},
     spawner::DriveFuture,
-    MemoryUsage,
+    InterruptHandler, MemoryUsage,
 };
 
 #[derive(Clone)]
@@ -91,7 +94,7 @@ impl AsyncRuntime {
     /// If the provided closure returns `true` the interpreter will raise and uncatchable
     /// exception and return control flow to the caller.
     #[inline]
-    pub async fn set_interrupt_handler(&self, handler: Option<Box<dyn FnMut() -> bool + 'static>>) {
+    pub async fn set_interrupt_handler(&self, handler: Option<InterruptHandler>) {
         unsafe {
             self.inner.lock().await.set_interrupt_handler(handler);
         }
diff --git a/core/src/runtime/base.rs b/core/src/runtime/base.rs
index 93bbad32..5a69a19f 100644
--- a/core/src/runtime/base.rs
+++ b/core/src/runtime/base.rs
@@ -10,7 +10,7 @@ use crate::allocator::Allocator;
 
 use super::{
     raw::{Opaque, RawRuntime},
-    MemoryUsage,
+    InterruptHandler, MemoryUsage,
 };
 
 /// A weak handle to the runtime.
@@ -72,7 +72,7 @@ impl Runtime {
     /// If the provided closure returns `true` the interpreter will raise and uncatchable
     /// exception and return control flow to the caller.
     #[inline]
-    pub fn set_interrupt_handler(&self, handler: Option<Box<dyn FnMut() -> bool + 'static>>) {
+    pub fn set_interrupt_handler(&self, handler: Option<InterruptHandler>) {
         unsafe {
             self.inner.lock().set_interrupt_handler(handler);
         }
diff --git a/core/src/runtime/raw.rs b/core/src/runtime/raw.rs
index ec842e29..f2bc6d63 100644
--- a/core/src/runtime/raw.rs
+++ b/core/src/runtime/raw.rs
@@ -11,6 +11,7 @@ use crate::{qjs, Function};
 
 #[cfg(feature = "futures")]
 use super::spawner::Spawner;
+use super::InterruptHandler;
 
 /// Opaque book keeping data for rust.
 pub(crate) struct Opaque<'js> {
@@ -18,7 +19,7 @@ pub(crate) struct Opaque<'js> {
     pub panic: Option<Box<dyn Any + Send + 'static>>,
 
     /// The user provided interrupt handler, if any.
-    pub interrupt_handler: Option<Box<dyn FnMut() -> bool + 'static>>,
+    pub interrupt_handler: Option<InterruptHandler>,
 
     #[cfg(feature = "futures")]
     pub spawner: Option<Spawner<'js>>,
@@ -233,10 +234,7 @@ impl RawRuntime {
     /// Set a closure which is regularly called by the engine when it is executing code.
     /// If the provided closure returns `true` the interpreter will raise and uncatchable
     /// exception and return control flow to the caller.
-    pub unsafe fn set_interrupt_handler(
-        &mut self,
-        handler: Option<Box<dyn FnMut() -> bool + 'static>>,
-    ) {
+    pub unsafe fn set_interrupt_handler(&mut self, handler: Option<InterruptHandler>) {
         unsafe extern "C" fn interrupt_handler_trampoline(
             _rt: *mut qjs::JSRuntime,
             opaque: *mut ::std::os::raw::c_void,