diff --git a/src/arena.c b/src/arena.c
index fc8a79c6..c971c12e 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -749,6 +749,7 @@ size_t _mi_arena_segment_abandoned_count(void) {
 }
 
 // reclaim a specific abandoned segment; `true` on success.
+// sets the thread_id.
 bool _mi_arena_segment_clear_abandoned(mi_segment_t* segment ) 
 {
   if (segment->memid.memkind != MI_MEM_ARENA) {
@@ -783,6 +784,7 @@ bool _mi_arena_segment_clear_abandoned(mi_segment_t* segment )
 }
 
 // mark a specific segment as abandoned
+// clears the thread_id.
 void _mi_arena_segment_mark_abandoned(mi_segment_t* segment) 
 {
   mi_atomic_store_release(&segment->thread_id, 0);
@@ -813,6 +815,7 @@ void _mi_arena_field_cursor_init(mi_heap_t* heap, mi_arena_field_cursor_t* curre
 }
 
 // reclaim abandoned segments 
+// this does not set the thread id (so it appears as still abandoned)
 mi_segment_t* _mi_arena_segment_clear_abandoned_next(mi_arena_field_cursor_t* previous ) 
 {
   const int max_arena = (int)mi_atomic_load_relaxed(&mi_arena_count);
@@ -845,7 +848,6 @@ mi_segment_t* _mi_arena_segment_clear_abandoned_next(mi_arena_field_cursor_t* pr
                 mi_assert_internal(_mi_bitmap_is_claimed(arena->blocks_inuse, arena->field_count, 1, bitmap_idx));
                 mi_segment_t* segment = (mi_segment_t*)mi_arena_block_start(arena, bitmap_idx);
                 mi_assert_internal(mi_atomic_load_relaxed(&segment->thread_id) == 0);
-                mi_atomic_store_release(&segment->thread_id, _mi_thread_id());
                 //mi_assert_internal(arena->blocks_committed == NULL || _mi_bitmap_is_claimed(arena->blocks_committed, arena->field_count, 1, bitmap_idx));
                 return segment;
               }
diff --git a/src/segment.c b/src/segment.c
index 3db4e813..a50f0190 100644
--- a/src/segment.c
+++ b/src/segment.c
@@ -845,7 +845,9 @@ static bool mi_segment_check_free(mi_segment_t* segment, size_t block_size, bool
 // set `right_page_reclaimed` to `true` if it reclaimed a page of the right `block_size` that was not full.
 static mi_segment_t* mi_segment_reclaim(mi_segment_t* segment, mi_heap_t* heap, size_t requested_block_size, bool* right_page_reclaimed, mi_segments_tld_t* tld) {
   if (right_page_reclaimed != NULL) { *right_page_reclaimed = false; }
-  mi_assert_internal(mi_atomic_load_relaxed(&segment->thread_id) == _mi_thread_id());
+  // can be 0 still with abandoned_next, or already a thread id for segments outside an arena that are reclaimed on a free.
+  mi_assert_internal(mi_atomic_load_relaxed(&segment->thread_id) == 0 || mi_atomic_load_relaxed(&segment->thread_id) == _mi_thread_id());
+  mi_atomic_store_release(&segment->thread_id, _mi_thread_id());
   segment->abandoned_visits = 0;
   mi_segments_track_size((long)segment->segment_size, tld);
   mi_assert_internal(segment->next == NULL && segment->prev == NULL);