diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index 82d74f7f..8d1e5149 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -106,7 +106,7 @@ terms of the MIT license. A copy of the license can be found in the file
 // Main tuning parameters for segment and page sizes
 // Sizes for 64-bit, divide by two for 32-bit
 #define MI_SEGMENT_SLICE_SHIFT            (13 + MI_INTPTR_SHIFT)         // 64KiB
-#define MI_SEGMENT_SHIFT                  ( 7 + MI_SEGMENT_SLICE_SHIFT)  //  8MiB
+#define MI_SEGMENT_SHIFT                  (10 + MI_SEGMENT_SLICE_SHIFT)  // 64MiB
 
 #define MI_SMALL_PAGE_SHIFT               (MI_SEGMENT_SLICE_SHIFT)       // 64KiB
 #define MI_MEDIUM_PAGE_SHIFT              ( 3 + MI_SMALL_PAGE_SHIFT)     // 512KiB
@@ -127,7 +127,7 @@ 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)  // 128KiB on 64-bit
 #define MI_MEDIUM_OBJ_WSIZE_MAX           (MI_MEDIUM_OBJ_SIZE_MAX/MI_INTPTR_SIZE)   
 
-#define MI_LARGE_OBJ_SIZE_MAX             (MI_SEGMENT_SIZE/2)      // 4MiB on 64-bit
+#define MI_LARGE_OBJ_SIZE_MAX             (MI_SEGMENT_SIZE/2)      // 32MiB 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)