diff --git a/bootloader_message/bootloader_message.cpp b/bootloader_message/bootloader_message.cpp
index b70d54e..1ea56cd 100644
--- a/bootloader_message/bootloader_message.cpp
+++ b/bootloader_message/bootloader_message.cpp
@@ -304,6 +304,16 @@
                                        offsetof(misc_system_space_layout, virtual_ab_message), err);
 }
 
+bool ReadMiscMemtagMessage(misc_memtag_message* message, std::string* err) {
+  return ReadMiscPartitionSystemSpace(message, sizeof(*message),
+                                      offsetof(misc_system_space_layout, memtag_message), err);
+}
+
+bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err) {
+  return WriteMiscPartitionSystemSpace(&message, sizeof(message),
+                                       offsetof(misc_system_space_layout, memtag_message), err);
+}
+
 extern "C" bool write_reboot_bootloader(void) {
   std::string err;
   return write_reboot_bootloader(&err);
diff --git a/bootloader_message/include/bootloader_message/bootloader_message.h b/bootloader_message/include/bootloader_message/bootloader_message.h
index e4cf09b..0d99273 100644
--- a/bootloader_message/include/bootloader_message/bootloader_message.h
+++ b/bootloader_message/include/bootloader_message/bootloader_message.h
@@ -93,18 +93,35 @@
   uint8_t reserved[57];
 } __attribute__((packed));
 
+struct misc_memtag_message {
+  uint8_t version;
+  uint32_t magic; // magic string for treble compat
+  uint32_t memtag_mode;
+  uint8_t reserved[55];
+} __attribute__((packed));
+
 #define MISC_VIRTUAL_AB_MESSAGE_VERSION 2
 #define MISC_VIRTUAL_AB_MAGIC_HEADER 0x56740AB0
 
+#define MISC_MEMTAG_MESSAGE_VERSION 1
+#define MISC_MEMTAG_MAGIC_HEADER 0x5afefe5a
+#define MISC_MEMTAG_MODE_MEMTAG 0x1
+#define MISC_MEMTAG_MODE_MEMTAG_ONCE 0x2
+#define MISC_MEMTAG_MODE_MEMTAG_KERNEL 0x4
+#define MISC_MEMTAG_MODE_MEMTAG_KERNEL_ONCE 0x8
+
 #if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus)
 static_assert(sizeof(struct misc_virtual_ab_message) == 64,
               "struct misc_virtual_ab_message has wrong size");
+static_assert(sizeof(struct misc_memtag_message) == 64,
+              "struct misc_virtual_ab_message has wrong size");
 #endif
 
 // This struct is not meant to be used directly, rather, it is to make
 // computation of offsets easier. New fields must be added to the end.
 struct misc_system_space_layout {
   misc_virtual_ab_message virtual_ab_message;
+  misc_memtag_message memtag_message;
 } __attribute__((packed));
 
 #ifdef __cplusplus
@@ -172,6 +189,9 @@
 bool ReadMiscVirtualAbMessage(misc_virtual_ab_message* message, std::string* err);
 bool WriteMiscVirtualAbMessage(const misc_virtual_ab_message& message, std::string* err);
 
+// Read or write the memtag message from system space in /misc.
+bool ReadMiscMemtagMessage(misc_memtag_message* message, std::string* err);
+bool WriteMiscMemtagMessage(const misc_memtag_message& message, std::string* err);
 #else
 
 #include <stdbool.h>