diff --git a/data/en_US/itin.json b/data/en_US/itin.json
index 71e402b..9ee1e71 100644
--- a/data/en_US/itin.json
+++ b/data/en_US/itin.json
@@ -1,5 +1,6 @@
 {
-  "format": "9{digits(2)}-{group}-{serial}",
+  "format": "{area}-{group}-{serial}",
+  "area": "9{digits(2)}",
   "group": [
     { "format": "{int(50,65)}", "weight": 16 },
     { "format": "{int(70,88)}", "weight": 19 },
diff --git a/data/en_US/person.json b/data/en_US/person.json
index b2c044c..79e66cd 100644
--- a/data/en_US/person.json
+++ b/data/en_US/person.json
@@ -2,6 +2,6 @@
   "format": "{prefix}{first} {last}",
   "first": "{.first-name.name}",
   "last": "{.last-name.name}",
-  "prefix": ["", { "format": "{.title.name} ", "weight": 0.1 }],
+  "prefix": [null, { "format": "{.title.name} ", "weight": 0.1 }],
   "sex": "{.sex.name}"
 }
diff --git a/data/sv_SE/person.json b/data/sv_SE/person.json
index 86d747a..d0fd81f 100644
--- a/data/sv_SE/person.json
+++ b/data/sv_SE/person.json
@@ -2,6 +2,6 @@
   "format": "{prefix}{first} {last}",
   "first": "{.first-name.name}",
   "last": "{.last-name.name}",
-  "prefix": ["", { "format": "{.title.name} ", "weight": 0.05 }],
+  "prefix": [null, { "format": "{.title.name} ", "weight": 0.05 }],
   "sex": "{.sex.name}"
 }