diff --git a/ext/data/schemas/dictionary-index-schema.json b/ext/data/schemas/dictionary-index-schema.json
index c2f095c7..a8ca0f23 100644
--- a/ext/data/schemas/dictionary-index-schema.json
+++ b/ext/data/schemas/dictionary-index-schema.json
@@ -46,6 +46,10 @@
             "type": "string",
             "description": "Attribution information for the dictionary data."
         },
+        "frequencyMode": {
+            "type": "string",
+            "enum": ["occurrence-based", "rank-based"]
+        },
         "tagMeta": {
             "type": "object",
             "description": "Tag information for terms and kanji. This object is obsolete and individual tag files should be used instead.",
diff --git a/ext/js/language/dictionary-importer.js b/ext/js/language/dictionary-importer.js
index 0a10900d..ad5d7a70 100644
--- a/ext/js/language/dictionary-importer.js
+++ b/ext/js/language/dictionary-importer.js
@@ -201,11 +201,12 @@ class DictionaryImporter {
             importDate: Date.now()
         };
 
-        const {author, url, description, attribution} = index;
+        const {author, url, description, attribution, frequencyMode} = index;
         if (typeof author === 'string') { summary.author = author; }
         if (typeof url === 'string') { summary.url = url; }
         if (typeof description === 'string') { summary.description = description; }
         if (typeof attribution === 'string') { summary.attribution = attribution; }
+        if (typeof frequencyMode === 'string') { summary.frequencyMode = frequencyMode; }
 
         Object.assign(summary, details);