diff --git a/include/evmc/evmc.h b/include/evmc/evmc.h
index 5ca265dae..f2200e26c 100644
--- a/include/evmc/evmc.h
+++ b/include/evmc/evmc.h
@@ -23,7 +23,7 @@ extern "C" {
 enum
 {
     /** The EVMC ABI version number of the interface declared in this file. */
-    EVMC_ABI_VERSION = 5
+    EVMC_ABI_VERSION = 6
 };
 
 /**
@@ -453,7 +453,12 @@ enum evmc_storage_status
     /**
      * A storage item has been deleted: X -> 0.
      */
-    EVMC_STORAGE_DELETED = 3
+    EVMC_STORAGE_DELETED = 3,
+
+    /**
+     * A storage item has been modified after being modified before: X -> Y -> Z.
+     */
+    EVMC_STORAGE_MODIFIED_DIRTY = 4
 };