diff --git a/CHANGELOG.md b/CHANGELOG.md
index e245aeb..d60608a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Change Log
 
+## 0.4.1 - 2024-03-24
+
+- Impl `Send` and `Sync` for `UnsafeWorldCell` and `Fetcher`.
+- Removed dependency on `memoffset`.
+
 ## 0.4.0 - 2024-03-09
 
 - Renamed "system" to "handler" to avoid confusion with other ECS libraries.
diff --git a/Cargo.toml b/Cargo.toml
index 6c40b76..bec8946 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,7 +16,7 @@ rayon = ["dep:rayon"]
 [dependencies]
 ahash = { version = "0.8.7", default-features = false }
 bumpalo = "3.14.0"
-evenio_macros = { path = "evenio_macros", version = "0.4.0" }
+evenio_macros = { path = "evenio_macros", version = "0.4.1" }
 hashbrown = { version = "0.14.3", default-features = false, features = [
     "inline-more",
 ] }
@@ -61,7 +61,7 @@ harness = false
 
 [workspace.package]
 edition = "2021"
-version = "0.4.0"
+version = "0.4.1"
 license = "MIT"
 repository = "https://github.com/rj00a/evenio"
 
diff --git a/src/fetch.rs b/src/fetch.rs
index dc5bf81..a269a81 100644
--- a/src/fetch.rs
+++ b/src/fetch.rs
@@ -960,4 +960,10 @@ mod tests {
 
         world.send(E1);
     }
+
+    fn _assert_auto_trait_impls<Q>()
+    where
+        for<'a> Fetcher<'a, Q>: Send + Sync,
+    {
+    }
 }
diff --git a/src/world.rs b/src/world.rs
index c59f31d..dd9fdf1 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -1104,6 +1104,11 @@ impl<'a> UnsafeWorldCell<'a> {
     }
 }
 
+// SAFETY: `&World` and `&mut World` are `Send`.
+unsafe impl Send for UnsafeWorldCell<'_> {}
+// SAFETY: `&World` and `&mut World` are `Sync`.
+unsafe impl Sync for UnsafeWorldCell<'_> {}
+
 #[cfg(test)]
 mod tests {
     use alloc::sync::Arc;
@@ -1222,6 +1227,8 @@ mod tests {
     fn _assert_auto_trait_impls()
     where
         World: Send + Sync + UnwindSafe + RefUnwindSafe,
+        for<'a> &'a World: Send + Sync,
+        for<'a> &'a mut World: Send + Sync,
     {
     }
 }