diff --git a/api/HTMLElement.json b/api/HTMLElement.json
index bea7d486d06760..c1ac91765c7c43 100644
--- a/api/HTMLElement.json
+++ b/api/HTMLElement.json
@@ -1278,10 +1278,17 @@
               "version_added": "≤79"
             },
             "firefox": {
-              "version_added": null
+              "version_added": "77",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "dom.forms.inputmode",
+                  "value_to_set": "true"
+                }
+              ]
             },
             "firefox_android": {
-              "version_added": null
+              "version_added": false
             },
             "ie": {
               "version_added": null
@@ -3594,4 +3601,4 @@
       }
     }
   }
-}
\ No newline at end of file
+}