diff --git a/user.js b/user.js
index 2544f76..5fa0e92 100644
--- a/user.js
+++ b/user.js
@@ -352,6 +352,15 @@ user_pref("browser.onboarding.enabled", false);
  * [1] https://github.com/mozilla-services/screenshots
  * [2] https://www.ghacks.net/2017/05/28/firefox-screenshots-integrated-in-firefox-nightly/ ***/
    // user_pref("extensions.screenshots.disabled", true);
+/* 0517: disable Form Autofill (also see 0864) (FF55+)
+ * [SETTING] Options>Privacy>Forms & Passwords>Enable Profile Autofill
+ * [NOTE] Stored data is NOT secure (uses a JSON file)
+ * [NOTE] Heuristics controls Form Autofill on forms without @autocomplete attributes
+ * [1] https://wiki.mozilla.org/Firefox/Features/Form_Autofill
+ * [2] https://www.ghacks.net/2017/05/24/firefoxs-new-form-autofill-is-awesome/ ***/
+user_pref("extensions.formautofill.addresses.enabled", false);
+user_pref("extensions.formautofill.experimental", false);
+user_pref("extensions.formautofill.heuristics.enabled", false);
 /* 0518: disable Web Compatibility Reporter (FF56+)
  * Web Compatibility Reporter adds a "Report Site Issue" button to send data to Mozilla ***/
 user_pref("extensions.webcompat-reporter.enabled", false);