diff --git a/share/twn_api.json b/share/twn_api.json
index 98dad5e..cf543df 100644
--- a/share/twn_api.json
+++ b/share/twn_api.json
@@ -308,7 +308,7 @@
             "header": "twn_util.h",
             "params": [
                 { "name": "value", "type": "Vec2" },
-                { "name": "identity", "type": "char *" }
+                { "name": "identity", "type": "char *", "default": {} }
             ]
         },
 
@@ -318,7 +318,7 @@
             "header": "twn_util.h",
             "params": [
                 { "name": "value", "type": "Vec3" },
-                { "name": "identity", "type": "char *" }
+                { "name": "identity", "type": "char *", "default": {} }
             ]
         },
 
@@ -328,7 +328,7 @@
             "header": "twn_util.h",
             "params": [
                 { "name": "value", "type": "Rect" },
-                { "name": "identity", "type": "char *" }
+                { "name": "identity", "type": "char *", "default": {} }
             ]
         },