--- libmalloc/libmalloc-374.60.3/src/nanov2_zone.h
+++ libmalloc/libmalloc-166.251.2/src/nanov2_zone.h
@@ -29,21 +29,21 @@
 #pragma mark -
 #pragma mark Address Structure
 
-#if TARGET_OS_OSX || TARGET_OS_SIMULATOR || TARGET_OS_DRIVERKIT
+#if TARGET_OS_OSX || TARGET_OS_SIMULATOR
 
 #define NANOV2_REGION_BITS		15
 #define NANOV2_ARENA_BITS		3
 #define NANOV2_BLOCK_BITS		12
 #define NANOV2_OFFSET_BITS		14
 
-#else // TARGET_OS_OSX || TARGET_OS_SIMULATOR || TARGET_OS_DRIVERKIT
+#else // TARGET_OS_OSX || TARGET_OS_SIMULATOR
 
 #define NANOV2_REGION_BITS		0
 #define NANOV2_ARENA_BITS		3
 #define NANOV2_BLOCK_BITS		12
 #define NANOV2_OFFSET_BITS		14
 
-#endif // TARGET_OS_OSX || TARGET_OS_SIMULATOR || TARGET_OS_DRIVERKIT
+#endif // TARGET_OS_OSX || TARGET_OS_SIMULATOR
 
 #if NANOV2_REGION_BITS > 0
 #define NANOV2_MULTIPLE_REGIONS	1
@@ -155,7 +155,6 @@
 
 // Distinguished values of next_slot
 #define SLOT_NULL			0		// Slot has never been used.
-#define SLOT_GUARD			0x7fa	// Marks a guard block.
 #define SLOT_BUMP 			0x7fb	// Marks the end of the free list
 #define SLOT_FULL			0x7fc	// Slot is full (no free slots)
 #define SLOT_CAN_MADVISE 	0x7fd	// Block can be madvised (and in_use == 0)