diff --git a/README.md b/README.md
index 908b2c9..6679e44 100644
--- a/README.md
+++ b/README.md
@@ -66,7 +66,7 @@ The Visual Studio 2017 Redistributable is required to run these builds.
 
 ## Building
 
-Requires Rust stable version 1.38.0 or newer to build.
+Requires Rust stable version 1.40.0 or newer to build.
 
 Compile and run:
 ```bash
diff --git a/appveyor.yml b/appveyor.yml
index 1295021..994ed6d 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -21,7 +21,7 @@ build_script:
 
     appveyor AddMessage "Platform rust: %RUST_INSTALL%"
 
-    appveyor DownloadFile "https://static.rust-lang.org/dist/rust-1.38.0-%RUST_INSTALL%.exe" -FileName rust-install.exe
+    appveyor DownloadFile "https://static.rust-lang.org/dist/rust-1.40.0-%RUST_INSTALL%.exe" -FileName rust-install.exe
 
     "./rust-install.exe" /VERYSILENT /NORESTART /DIR="C:\Rust\"
 
diff --git a/src/ecs/mod.rs b/src/ecs/mod.rs
index e63c4a9..2fa3fd5 100644
--- a/src/ecs/mod.rs
+++ b/src/ecs/mod.rs
@@ -481,7 +481,7 @@ impl ComponentMem {
             component_size: mem::size_of::<T>(),
             drop_func: Box::new(|data| {
                 unsafe {
-                    let mut val: T = mem::uninitialized();
+                    let mut val: T = mem::MaybeUninit::uninit().assume_init();
                     ptr::copy(data as *mut T, &mut val, 1);
                     mem::drop(val);
                 }