diff --git a/include/mimalloc/types.h b/include/mimalloc/types.h
index 0115fbdb..cd3ddf63 100644
--- a/include/mimalloc/types.h
+++ b/include/mimalloc/types.h
@@ -451,6 +451,7 @@ typedef struct mi_segment_s {
   bool              allow_decommit;     // can we decommmit the memory
   bool              allow_purge;        // can we purge the memory (reset or decommit)
   size_t            segment_size;
+  mi_subproc_t*     subproc;            // segment belongs to sub process
 
   // segment fields
   mi_msecs_t        purge_expire;       // purge slices in the `purge_mask` after this time
@@ -465,7 +466,6 @@ typedef struct mi_segment_s {
   size_t            abandoned_visits;   // count how often this segment is visited during abondoned reclamation (to force reclaim if it takes too long)
   size_t            used;               // count of pages in use
   uintptr_t         cookie;             // verify addresses in debug mode: `mi_ptr_cookie(segment) == segment->cookie`
-  mi_subproc_t*     subproc;            // segment belongs to sub process
 
   struct mi_segment_s* abandoned_os_next; // only used for abandoned segments outside arena's, and only if `mi_option_visit_abandoned` is enabled
   struct mi_segment_s* abandoned_os_prev;
diff --git a/src/arena-abandoned.c b/src/arena-abandoned.c
index 3b1b1823..465a074d 100644
--- a/src/arena-abandoned.c
+++ b/src/arena-abandoned.c
@@ -162,8 +162,9 @@ void _mi_arena_segment_mark_abandoned(mi_segment_t* segment)
   mi_arena_t* arena = mi_arena_from_index(arena_idx);
   mi_assert_internal(arena != NULL);
   // set abandonment atomically
+  mi_subproc_t* const subproc = segment->subproc; // don't access the segment after setting it abandoned
   const bool was_unmarked = _mi_bitmap_claim(arena->blocks_abandoned, arena->field_count, 1, bitmap_idx, NULL);
-  if (was_unmarked) { mi_atomic_increment_relaxed(&segment->subproc->abandoned_count); }
+  if (was_unmarked) { mi_atomic_increment_relaxed(&subproc->abandoned_count); }
   mi_assert_internal(was_unmarked);
   mi_assert_internal(_mi_bitmap_is_claimed(arena->blocks_inuse, arena->field_count, 1, bitmap_idx));
 }
diff --git a/src/arena.c b/src/arena.c
index 9c1ca59f..9111243e 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -631,6 +631,9 @@ void _mi_arena_free(void* p, size_t size, size_t committed_size, mi_memid_t memi
   if (size==0) return;
   const bool all_committed = (committed_size == size);
 
+  // need to set all memory to undefined as some parts may still be marked as no_access (like padding etc.)
+  mi_track_mem_undefined(p,size);
+
   if (mi_memkind_is_os(memid.memkind)) {
     // was a direct OS allocation, pass through
     if (!all_committed && committed_size > 0) {
@@ -660,9 +663,6 @@ void _mi_arena_free(void* p, size_t size, size_t committed_size, mi_memid_t memi
       return;
     }
 
-    // need to set all memory to undefined as some parts may still be marked as no_access (like padding etc.)
-    mi_track_mem_undefined(p,size);
-
     // potentially decommit
     if (arena->memid.is_pinned || arena->blocks_committed == NULL) {
       mi_assert_internal(all_committed);
diff --git a/src/init.c b/src/init.c
index 784c8b37..0f3142b5 100644
--- a/src/init.c
+++ b/src/init.c
@@ -193,7 +193,7 @@ static void mi_heap_main_init(void) {
     #endif
     _mi_heap_main.cookie  = _mi_heap_random_next(&_mi_heap_main);
     _mi_heap_main.keys[0] = _mi_heap_random_next(&_mi_heap_main);
-    _mi_heap_main.keys[1] = _mi_heap_random_next(&_mi_heap_main);    
+    _mi_heap_main.keys[1] = _mi_heap_random_next(&_mi_heap_main);
     mi_lock_init(&mi_subproc_default.abandoned_os_lock);
     mi_lock_init(&mi_subproc_default.abandoned_os_visit_lock);
   }
@@ -363,7 +363,7 @@ static bool _mi_thread_heap_init(void) {
     mi_heap_t* heap = &td->heap;
     _mi_tld_init(tld, heap);  // must be before `_mi_heap_init`
     _mi_heap_init(heap, tld, _mi_arena_id_none(), false /* can reclaim */, 0 /* default tag */);
-    _mi_heap_set_default_direct(heap);   
+    _mi_heap_set_default_direct(heap);
   }
   return false;
 }
diff --git a/src/segment.c b/src/segment.c
index ab4f8bdd..5b23ce76 100644
--- a/src/segment.c
+++ b/src/segment.c
@@ -857,6 +857,7 @@ static mi_segment_t* mi_segment_os_alloc( size_t required, size_t page_alignment
   segment->allow_decommit = !memid.is_pinned;
   segment->allow_purge = segment->allow_decommit && (mi_option_get(mi_option_purge_delay) >= 0);
   segment->segment_size = segment_size;
+  segment->subproc = tld->subproc;
   segment->commit_mask = commit_mask;
   segment->purge_expire = 0;
   mi_commit_mask_create_empty(&segment->purge_mask);
@@ -903,7 +904,6 @@ static mi_segment_t* mi_segment_alloc(size_t required, size_t page_alignment, mi
   segment->segment_info_slices = info_slices;
   segment->thread_id = _mi_thread_id();
   segment->cookie = _mi_ptr_cookie(segment);
-  segment->subproc = tld->subproc;
   segment->slice_entries = slice_entries;
   segment->kind = (required == 0 ? MI_SEGMENT_NORMAL : MI_SEGMENT_HUGE);
 
diff --git a/test/test-stress.c b/test/test-stress.c
index d559d69f..c6a64130 100644
--- a/test/test-stress.c
+++ b/test/test-stress.c
@@ -25,17 +25,14 @@ terms of the MIT license.
 // > mimalloc-test-stress [THREADS] [SCALE] [ITER]
 //
 // argument defaults
+#if !defined(MI_TSAN)
 static int THREADS = 32;      // more repeatable if THREADS <= #processors
-static int SCALE   = 25;      // scaling factor
-
-#if defined(MI_TSAN)
-static int ITER    = 10;      // N full iterations destructing and re-creating all threads (on tsan reduce for azure pipeline limits)
-#else
-static int ITER    = 50;      // N full iterations destructing and re-creating all threads
+#else                         // with thread-sanitizer reduce the defaults for azure pipeline limits
+static int THREADS = 8;
 #endif
 
-// static int THREADS = 8;    // more repeatable if THREADS <= #processors
-// static int SCALE   = 100;  // scaling factor
+static int SCALE   = 25;      // scaling factor
+static int ITER    = 50;      // N full iterations destructing and re-creating all threads
 
 #define STRESS                // undefine for leak test
 
@@ -133,9 +130,9 @@ static void free_items(void* p) {
   custom_free(p);
 }
 
-#ifdef HEAP_WALK 
+#ifdef HEAP_WALK
 static bool visit_blocks(const mi_heap_t* heap, const mi_heap_area_t* area, void* block, size_t block_size, void* arg) {
-  (void)(heap); (void)(area); 
+  (void)(heap); (void)(area);
   size_t* total = (size_t*)arg;
   if (block != NULL) {
     *total += block_size;
@@ -260,7 +257,7 @@ static void test_leak(void) {
 
 int main(int argc, char** argv) {
   #ifdef HEAP_WALK
-    mi_option_enable(mi_option_visit_abandoned);    
+    mi_option_enable(mi_option_visit_abandoned);
   #endif
   #ifndef NDEBUG
     mi_option_set(mi_option_arena_reserve, 32 * 1024 /* in kib = 32MiB */);