diff --git a/wgpu-core/src/id.rs b/wgpu-core/src/id.rs
index 83b249439..19baa2e6f 100644
--- a/wgpu-core/src/id.rs
+++ b/wgpu-core/src/id.rs
@@ -11,7 +11,7 @@ type IdType = u64;
 type ZippedIndex = Index;
 type NonZeroId = std::num::NonZeroU64;
 
-const INDEX_BITS: usize = std::mem::size_of::<ZippedIndex>() * 8;
+const INDEX_BITS: usize = ZippedIndex::BITS as usize;
 const EPOCH_BITS: usize = INDEX_BITS - BACKEND_BITS;
 const BACKEND_BITS: usize = 3;
 const BACKEND_SHIFT: usize = INDEX_BITS * 2 - BACKEND_BITS;
diff --git a/wgpu-core/src/track/metadata.rs b/wgpu-core/src/track/metadata.rs
index 855282d72..22576207a 100644
--- a/wgpu-core/src/track/metadata.rs
+++ b/wgpu-core/src/track/metadata.rs
@@ -1,7 +1,6 @@
 //! The `ResourceMetadata` type.
 
 use bit_vec::BitVec;
-use std::mem;
 use wgt::strict_assert;
 
 /// A set of resources, holding a `Arc<T>` and epoch for each member.
@@ -191,7 +190,7 @@ fn resize_bitvec<B: bit_vec::BitBlock>(vec: &mut BitVec<B>, size: usize) {
 ///
 /// Will skip entire usize's worth of bits if they are all false.
 fn iterate_bitvec_indices(ownership: &BitVec<usize>) -> impl Iterator<Item = usize> + '_ {
-    const BITS_PER_BLOCK: usize = mem::size_of::<usize>() * 8;
+    const BITS_PER_BLOCK: usize = usize::BITS as usize;
 
     let size = ownership.len();