diff --git a/src_features/signMessageEIP712/eip712.h b/src_features/signMessageEIP712/eip712.h
index 41c54f9..26ed8d1 100644
--- a/src_features/signMessageEIP712/eip712.h
+++ b/src_features/signMessageEIP712/eip712.h
@@ -57,6 +57,13 @@ typedef enum
 #define TYPESIZE_MASK   (1 << 6)
 #define TYPENAME_ENUM   (0xF)
 
+typedef enum
+{
+    EIP712_TYPE_HASH,
+    EIP712_FIELD_HASH,
+    EIP712_STRUCT_HASH
+}   e_eip712_hash_type;
+
 #define KECCAK256_HASH_BYTESIZE 32
 
 #define ARRAY_SIZE(a)   (sizeof(a) / sizeof(a[0]))
diff --git a/src_features/signMessageEIP712/type_hash.c b/src_features/signMessageEIP712/type_hash.c
index bd5680e..3ccad3c 100644
--- a/src_features/signMessageEIP712/type_hash.c
+++ b/src_features/signMessageEIP712/type_hash.c
@@ -37,23 +37,27 @@ const uint8_t *type_hash(const void *const structs_array,
     // restore the memory location
     mem_dealloc(mem_alloc(0) - mem_loc_bak);
 
-    // copy hash into memory
-    if ((hash_ptr = mem_alloc(KECCAK256_HASH_BYTESIZE)) == NULL)
+    if ((hash_ptr = mem_alloc(KECCAK256_HASH_BYTESIZE + 1)) == NULL)
     {
         return NULL;
     }
+
+    // set TypeHash marker
+    *hash_ptr = EIP712_TYPE_HASH;
+
+    // copy hash into memory
     cx_hash((cx_hash_t*)&global_sha3,
             CX_LAST,
             NULL,
             0,
-            hash_ptr,
+            hash_ptr + 1,
             KECCAK256_HASH_BYTESIZE);
 #ifdef DEBUG
     // print computed hash
     printf("-> 0x");
     for (int idx = 0; idx < KECCAK256_HASH_BYTESIZE; ++idx)
     {
-        printf("%.02x", hash_ptr[idx]);
+        printf("%.02x", (hash_ptr + 1)[idx]);
     }
     printf("\n");
 #endif