diff --git a/include/evmc/evmc.h b/include/evmc/evmc.h
index 064d3f8..22b064b 100644
--- a/include/evmc/evmc.h
+++ b/include/evmc/evmc.h
@@ -40,7 +40,7 @@ extern "C" {
 enum
 {
     /** The EVMC ABI version number of the interface declared in this file. */
-    EVMC_ABI_VERSION = 1
+    EVMC_ABI_VERSION = 2
 };
 
 /**
@@ -68,10 +68,11 @@ struct evmc_address
 enum evmc_call_kind
 {
     EVMC_CALL = 0,         /**< Request CALL. */
-    EVMC_DELEGATECALL = 1, /**< Request DELEGATECALL. The value param ignored. */
+    EVMC_DELEGATECALL = 1, /**< Request DELEGATECALL. Valid since Homestead.
+                                The value param ignored. */
     EVMC_CALLCODE = 2,     /**< Request CALLCODE. */
-    EVMC_CREATE = 3,       /**< Request CREATE. Semantic of some params changes. */
-    EVMC_CREATE2 = 4       /**< Request CREATE2. Semantic of some params changes. */
+    EVMC_CREATE = 3,       /**< Request CREATE. */
+    EVMC_CREATE2 = 4       /**< Request CREATE2. Valid since Constantinople.*/
 };
 
 /** The flags for ::evmc_message. */
@@ -117,6 +118,13 @@ struct evmc_message
      */
     struct evmc_uint256be code_hash;
 
+    /**
+     * The optional value used in new contract address construction.
+     *
+     *  Ignored unless kind is EVMC_CREATE2.
+     */
+    struct evmc_uint256be create2_salt;
+
     /** The amount of gas for message execution. */
     int64_t gas;
 
diff --git a/test/vmtester/tests.cpp b/test/vmtester/tests.cpp
index a284412..744c97b 100644
--- a/test/vmtester/tests.cpp
+++ b/test/vmtester/tests.cpp
@@ -12,7 +12,6 @@ static_assert(sizeof(evmc_uint256be) == 32, "evmc_uint256be is too big");
 static_assert(sizeof(evmc_address) == 20, "evmc_address is too big");
 static_assert(sizeof(evmc_result) <= 64, "evmc_result does not fit cache line");
 static_assert(sizeof(evmc_instance) <= 64, "evmc_instance does not fit cache line");
-static_assert(sizeof(evmc_message) <= 18 * 8, "evmc_message not optimally packed");
 static_assert(offsetof(evmc_message, code_hash) % 8 == 0, "evmc_message.code_hash not aligned");
 
 // Check enums match int size.