2 files changed, 2 insertions, 0 deletions
diff --git a/library/std/src/sys/unsupported/mutex.rs b/library/std/src/sys/unsupported/mutex.rs
index 3b97d0875bd..7830faae601 100644
--- a/library/std/src/sys/unsupported/mutex.rs
+++ b/library/std/src/sys/unsupported/mutex.rs
@@ -1,6 +1,7 @@
 use crate::cell::Cell;
 
 pub struct Mutex {
+    // This platform has no threads, so we can use a Cell here.
     locked: Cell<bool>,
 }
 
diff --git a/library/std/src/sys/unsupported/rwlock.rs b/library/std/src/sys/unsupported/rwlock.rs
index 9aaba8bff11..6982b2b155f 100644
--- a/library/std/src/sys/unsupported/rwlock.rs
+++ b/library/std/src/sys/unsupported/rwlock.rs
@@ -1,6 +1,7 @@
 use crate::cell::Cell;
 
 pub struct RWLock {
+    // This platform has no threads, so we can use a Cell here.
     mode: Cell<isize>,
 }