diff --git a/substrate/substrate/pwasm-alloc/src/lib.rs b/substrate/substrate/pwasm-alloc/src/lib.rs
index 85be153815..bf4e33f133 100644
--- a/substrate/substrate/pwasm-alloc/src/lib.rs
+++ b/substrate/substrate/pwasm-alloc/src/lib.rs
@@ -20,16 +20,16 @@ mod __impl {
 	extern crate alloc;
 	extern crate pwasm_libc;
 
-	use self::alloc::heap::{GlobalAlloc, Layout, Opaque};
+	use core::alloc::{GlobalAlloc, Layout};
 
 	use super::WasmAllocator;
 
 	unsafe impl GlobalAlloc for WasmAllocator {
-		unsafe fn alloc(&self, layout: Layout) -> *mut Opaque {
-			pwasm_libc::malloc(layout.size()) as *mut Opaque
+		unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+			pwasm_libc::malloc(layout.size()) as *mut u8
 		}
 
-		unsafe fn dealloc(&self, ptr: *mut Opaque, _layout: Layout) {
+		unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
 			pwasm_libc::free(ptr as *mut u8)
 		}
 	}