diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index 931d3270..6af46d18 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -122,7 +122,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #define MI_MEDIUM_OBJ_SIZE_MAX            (MI_MEDIUM_PAGE_SIZE/4)  // 128kb on 64-bit
 #define MI_MEDIUM_OBJ_WSIZE_MAX           (MI_MEDIUM_OBJ_SIZE_MAX/MI_INTPTR_SIZE)   // 64kb on 64-bit
 
-#define MI_LARGE_OBJ_SIZE_MAX             (MI_SEGMENT_SIZE/2)      // 32mb on 64-bit
+#define MI_LARGE_OBJ_SIZE_MAX             (MI_SEGMENT_SIZE/2)      // 4mb on 64-bit
 #define MI_LARGE_OBJ_WSIZE_MAX            (MI_LARGE_OBJ_SIZE_MAX/MI_INTPTR_SIZE)
 
 #define MI_HUGE_OBJ_SIZE_MAX              (2*MI_INTPTR_SIZE*MI_SEGMENT_SIZE)        // (must match MI_REGION_MAX_ALLOC_SIZE in memory.c)
diff --git a/src/arena.c b/src/arena.c
index 959d59c5..6a15c83d 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -8,7 +8,7 @@ terms of the MIT license. A copy of the license can be found in the file
 
 /* ----------------------------------------------------------------------------
 "Arenas" are fixed area's of OS memory from which we can allocate
-large blocks (>= MI_ARENA_BLOCK_SIZE, 32MiB).
+large blocks (>= MI_ARENA_BLOCK_SIZE, 8MiB).
 In contrast to the rest of mimalloc, the arenas are shared between
 threads and need to be accessed using atomic operations.
 
@@ -55,9 +55,9 @@ bool  _mi_os_commit(void* p, size_t size, bool* is_zero, mi_stats_t* stats);
 // size in count of arena blocks.
 typedef uintptr_t mi_block_info_t;
 #define MI_SEGMENT_ALIGN      MI_SEGMENT_SIZE
-#define MI_ARENA_BLOCK_SIZE   MI_SEGMENT_ALIGN         // 64MiB
-#define MI_ARENA_MAX_OBJ_SIZE (MI_BITMAP_FIELD_BITS * MI_ARENA_BLOCK_SIZE)  // 4GiB
-#define MI_ARENA_MIN_OBJ_SIZE (MI_ARENA_BLOCK_SIZE/2)  // 32MiB
+#define MI_ARENA_BLOCK_SIZE   MI_SEGMENT_ALIGN         // 8MiB
+#define MI_ARENA_MAX_OBJ_SIZE (MI_BITMAP_FIELD_BITS * MI_ARENA_BLOCK_SIZE)  // 512MiB
+#define MI_ARENA_MIN_OBJ_SIZE (MI_ARENA_BLOCK_SIZE/2)  // 4MiB
 #define MI_MAX_ARENAS         (64)                     // not more than 256 (since we use 8 bits in the memid)
 
 // A memory arena descriptor
diff --git a/src/region.c b/src/region.c
index e916e452..db2871d6 100644
--- a/src/region.c
+++ b/src/region.c
@@ -88,12 +88,12 @@ typedef union mi_region_info_u {
 typedef struct mem_region_s {
   _Atomic(uintptr_t)        info;        // mi_region_info_t.value
   _Atomic(void*)            start;       // start of the memory area 
-  mi_bitmap_field_t                  in_use;      // bit per in-use block
-  mi_bitmap_field_t                  dirty;       // track if non-zero per block
-  mi_bitmap_field_t                  commit;      // track if committed per block
-  mi_bitmap_field_t                  reset;       // track if reset per block
+  mi_bitmap_field_t         in_use;      // bit per in-use block
+  mi_bitmap_field_t         dirty;       // track if non-zero per block
+  mi_bitmap_field_t         commit;      // track if committed per block
+  mi_bitmap_field_t         reset;       // track if reset per block
   _Atomic(uintptr_t)        arena_memid; // if allocated from a (huge page) arena
-  uintptr_t                          padding;     // round to 8 fields
+  uintptr_t                 padding;     // round to 8 fields
 } mem_region_t;
 
 // The region map