diff --git a/src/heap/slot-set.h b/src/heap/slot-set.h
index 9229710453..c71192bfdc 100644
--- a/src/heap/slot-set.h
+++ b/src/heap/slot-set.h
@@ -52,9 +52,6 @@ class SlotSet : public Malloced {
   void SetPageStart(Address page_start) { page_start_ = page_start; }
 
   // The slot offset specifies a slot at address page_start_ + slot_offset.
-  // This method should only be called on the main thread because concurrent
-  // allocation of the bucket is not thread-safe.
-  //
   // AccessMode defines whether there can be concurrent access on the buckets
   // or not.
   template <AccessMode access_mode = AccessMode::ATOMIC>
@@ -181,7 +178,10 @@ class SlotSet : public Malloced {
   // Iterate over all slots in the set and for each slot invoke the callback.
   // If the callback returns REMOVE_SLOT then the slot is removed from the set.
   // Returns the new number of slots.
-  // This method should only be called on the main thread.
+  //
+  // Iteration can be performed concurrently with other operations that use
+  // atomic access mode such as insertion and removal. However there is no
+  // guarantee about ordering and linearizability.
   //
   // Sample usage:
   // Iterate([](MaybeObjectSlot slot) {