diff --git a/zeroize/src/lib.rs b/zeroize/src/lib.rs
index e6664c1f..1166d83c 100644
--- a/zeroize/src/lib.rs
+++ b/zeroize/src/lib.rs
@@ -805,6 +805,10 @@ unsafe fn volatile_set<T: Copy + Sized>(dst: *mut T, src: T, count: usize) {
 #[inline(always)]
 pub unsafe fn zeroize_flat_type<T: Sized>(data: *mut T) {
     let size = mem::size_of::<T>();
+    // Safety:
+    //
+    // This is safe because `mem::size_of<T>()` returns the exact size of the object in memory, and
+    // `data_ptr` points directly to the first byte of the data.
     volatile_set(data as *mut u8, 0, size);
     atomic_fence()
 }