diff --git a/json-schema/forked-schema.json b/json-schema/forked-schema.json
index cfb3b6e6d..aaf97f4e6 100644
--- a/json-schema/forked-schema.json
+++ b/json-schema/forked-schema.json
@@ -13,7 +13,11 @@
     },
     "lang": {
       "description": "Comma-separated list of ISO 639-1 codes targeted by the list.",
-      "type": "string"
+      "type": "array",
+      "items": {
+        "type": "string"
+      },
+      "uniqueItems": true
     },
     "descr": {
       "description": "A brief description of the list's functionality. Preferably, this is quoted (includes translation to English via translator or Google Translate) from the list's documentation or composed by a maintainer of the list. If neither are available, a generic description should be composed by the FilterLists contributer.",
diff --git a/json-schema/regional-schema.json b/json-schema/regional-schema.json
index c83f0a26c..5edb95380 100644
--- a/json-schema/regional-schema.json
+++ b/json-schema/regional-schema.json
@@ -14,7 +14,11 @@
     },
     "lang": {
       "description": "Comma-separated list of ISO 639-1 codes targeted by the list.",
-      "type": "string"
+      "type": "array",
+      "items": {
+        "type": "string"
+      },
+      "uniqueItems": true
     },
     "descr": {
       "description": "A brief description of the list's functionality. Preferably, this is quoted (includes translation to English via translator or Google Translate) from the list's documentation or composed by a maintainer of the list. If neither are available, a generic description should be composed by the FilterLists contributer.",
diff --git a/json-schema/stale-schema.json b/json-schema/stale-schema.json
index c40231853..09ed88ee3 100644
--- a/json-schema/stale-schema.json
+++ b/json-schema/stale-schema.json
@@ -13,7 +13,11 @@
     },
     "lang": {
       "description": "Comma-separated list of ISO 639-1 codes targeted by the list.",
-      "type": "string"
+      "type": "array",
+      "items": {
+        "type": "string"
+      },
+      "uniqueItems": true
     },
     "descr": {
       "description": "A brief description of the list's functionality. Preferably, this is quoted (includes translation to English via translator or Google Translate) from the list's documentation or composed by a maintainer of the list. If neither are available, a generic description should be composed by the FilterLists contributer.",