diff --git a/src/eth_plugin_handler.c b/src/eth_plugin_handler.c
index 67cab66..da1cac9 100644
--- a/src/eth_plugin_handler.c
+++ b/src/eth_plugin_handler.c
@@ -146,6 +146,8 @@ eth_plugin_result_t eth_plugin_call(int method, void *parameter) {
 
     switch (method) {
         case ETH_PLUGIN_INIT_CONTRACT:
+            ((ethPluginInitContract_t *) parameter)->interfaceVersion =
+                ETH_PLUGIN_INTERFACE_VERSION_1;
             ((ethPluginInitContract_t *) parameter)->result = ETH_PLUGIN_RESULT_UNAVAILABLE;
             ((ethPluginInitContract_t *) parameter)->pluginSharedRW = &pluginRW;
             ((ethPluginInitContract_t *) parameter)->pluginSharedRO = &pluginRO;
diff --git a/src/eth_plugin_interface.h b/src/eth_plugin_interface.h
index 792d36f..524bc0f 100644
--- a/src/eth_plugin_interface.h
+++ b/src/eth_plugin_interface.h
@@ -9,6 +9,10 @@
 
 #define PLUGIN_ID_LENGTH 30
 
+typedef enum {
+    ETH_PLUGIN_INTERFACE_VERSION_1 = 1  // Version 1
+} eth_plugin_interface_version_t;
+
 typedef enum {
 
     ETH_PLUGIN_INIT_CONTRACT = 0x0101,
@@ -61,8 +65,10 @@ typedef struct ethPluginSharedRO_t {
 // Init Contract
 
 typedef struct ethPluginInitContract_t {
-    // in
+    uint8_t interfaceVersion;
+    uint8_t result;
 
+    // in
     ethPluginSharedRW_t *pluginSharedRW;
     ethPluginSharedRO_t *pluginSharedRO;
     uint8_t *pluginContext;
@@ -72,8 +78,6 @@ typedef struct ethPluginInitContract_t {
 
     char *alias;  // 29 bytes alias if ETH_PLUGIN_RESULT_OK_ALIAS set
 
-    uint8_t result;
-
 } ethPluginInitContract_t;
 
 // Provide parameter