diff --git a/py/map.c b/py/map.c
index d40e3dc4d0..f6efbcc085 100644
--- a/py/map.c
+++ b/py/map.c
@@ -32,6 +32,7 @@
 #include "py/mpconfig.h"
 #include "py/misc.h"
 #include "py/runtime.h"
+#include "py/mphal.h"
 
 #if MICROPY_DEBUG_VERBOSE // print debugging info
 #define DEBUG_PRINT (1)
@@ -134,16 +135,28 @@ static void mp_map_rehash(mp_map_t *map) {
     DEBUG_printf("mp_map_rehash(%p): " UINT_FMT " -> " UINT_FMT "\n", map, old_alloc, new_alloc);
     mp_map_elem_t *old_table = map->table;
     mp_map_elem_t *new_table = m_new0(mp_map_elem_t, new_alloc);
-    // If we reach this point, table resizing succeeded, now we can edit the old map.
-    map->alloc = new_alloc;
-    map->used = 0;
-    map->all_keys_are_qstrs = 1;
-    map->table = new_table;
+
+    // If we reach this point then allocating the new table succeeded, so construct the new map.
+    mp_map_t new_map = {
+        .all_keys_are_qstrs = 1,
+        .is_fixed = 0,
+        .is_ordered = 0,
+        .used = 0,
+        .alloc = new_alloc,
+        .table = new_table,
+    };
     for (size_t i = 0; i < old_alloc; i++) {
         if (old_table[i].key != MP_OBJ_NULL && old_table[i].key != MP_OBJ_SENTINEL) {
-            mp_map_lookup(map, old_table[i].key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = old_table[i].value;
+            mp_map_lookup(&new_map, old_table[i].key, MP_MAP_LOOKUP_ADD_IF_NOT_FOUND)->value = old_table[i].value;
         }
     }
+
+    // Swap the old map for the new one.
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+    *map = new_map;
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+
+    // Free the old table.
     m_del(mp_map_elem_t, old_table, old_alloc);
 }
 
diff --git a/tests/thread/stress_globals.py b/tests/thread/stress_globals.py
new file mode 100644
index 0000000000..fe2f77b9ef
--- /dev/null
+++ b/tests/thread/stress_globals.py
@@ -0,0 +1,79 @@
+import time, _thread
+
+
+def thread_task():
+    for _ in range(1000):
+        a00
+    print("pass")
+
+
+print("start")
+a00 = None
+
+_thread.start_new_thread(thread_task, ())
+
+# create lots of global variables
+a01 = None
+a02 = None
+a03 = None
+a04 = None
+a05 = None
+a06 = None
+a07 = None
+a10 = None
+a11 = None
+a12 = None
+a13 = None
+a14 = None
+a15 = None
+a16 = None
+a17 = None
+a18 = None
+a19 = None
+a20 = None
+a21 = None
+a22 = None
+a23 = None
+a24 = None
+a25 = None
+a26 = None
+a27 = None
+a28 = None
+a29 = None
+a30 = None
+a31 = None
+a32 = None
+a33 = None
+a34 = None
+a35 = None
+a36 = None
+a37 = None
+a38 = None
+a39 = None
+a40 = None
+a41 = None
+a42 = None
+a43 = None
+a44 = None
+a45 = None
+a46 = None
+a47 = None
+a48 = None
+a49 = None
+a50 = None
+a51 = None
+a52 = None
+a53 = None
+a54 = None
+a55 = None
+a56 = None
+a57 = None
+a58 = None
+a59 = None
+a60 = None
+a61 = None
+a62 = None
+a63 = None
+
+# let the thread finish
+time.sleep(0.1)