diff --git a/napi/src/task.rs b/napi/src/task.rs
index 3951a403..7ff0ffb8 100644
--- a/napi/src/task.rs
+++ b/napi/src/task.rs
@@ -4,7 +4,7 @@ pub trait Task {
   type Output: Send + Sized + 'static;
   type JsValue: ValueType;
 
-  fn compute(&self) -> Result<Self::Output>;
+  fn compute(&mut self) -> Result<Self::Output>;
 
   fn resolve(&self, env: &mut Env, output: Self::Output) -> Result<Value<Self::JsValue>>;
 }
diff --git a/test_module/src/lib.rs b/test_module/src/lib.rs
index 12766e82..8b690273 100644
--- a/test_module/src/lib.rs
+++ b/test_module/src/lib.rs
@@ -51,7 +51,7 @@ impl Task for ComputeFib {
   type Output = u32;
   type JsValue = Number;
 
-  fn compute(&self) -> Result<Self::Output> {
+  fn compute(&mut self) -> Result<Self::Output> {
     Ok(fibonacci_native(self.n))
   }