diff --git a/addon/bootstrap.js b/addon/bootstrap.js
index c9f4d15..b3ad9e6 100644
--- a/addon/bootstrap.js
+++ b/addon/bootstrap.js
@@ -64,6 +64,11 @@ function install(data, reason) {}
 async function startup({ id, version, resourceURI, rootURI }, reason) {
   await waitForZotero();
 
+  // String 'rootURI' introduced in Zotero 7
+  if (!rootURI) {
+    rootURI = resourceURI.spec;
+  }
+
   if (Zotero.platformMajorVersion >= 102) {
     var aomStartup = Components.classes[
       "@mozilla.org/addons/addon-manager-startup;1"
@@ -74,11 +79,10 @@ async function startup({ id, version, resourceURI, rootURI }, reason) {
       ["locale", "__addonRef__", "en-US", rootURI + "chrome/locale/en-US/"],
       ["locale", "__addonRef__", "zh-CN", rootURI + "chrome/locale/zh-CN/"],
     ]);
-  }
-
-  // String 'rootURI' introduced in Zotero 7
-  if (!rootURI) {
-    rootURI = resourceURI.spec;
+  } else {
+    if (reason == ADDON_INSTALL || reason == ADDON_ENABLE) {
+      setDefaultPrefs(rootURI);
+    }
   }
 
   // Global variables for plugin code
@@ -117,3 +121,27 @@ function shutdown({ id, version, resourceURI, rootURI }, reason) {
 }
 
 function uninstall(data, reason) {}
+
+// Loads default preferences from defaults/preferences/prefs.js in Zotero 6
+function setDefaultPrefs(rootURI) {
+  var branch = Services.prefs.getDefaultBranch("");
+  var obj = {
+    pref(pref, value) {
+      switch (typeof value) {
+        case "boolean":
+          branch.setBoolPref(pref, value);
+          break;
+        case "string":
+          branch.setStringPref(pref, value);
+          break;
+        case "number":
+          branch.setIntPref(pref, value);
+          break;
+        default:
+          Zotero.logError(`Invalid type '${typeof value}' for pref '${pref}'`);
+      }
+    },
+  };
+  Zotero.getMainWindow().console.log(rootURI + "prefs.js");
+  Services.scriptloader.loadSubScript(rootURI + "prefs.js", obj);
+}
diff --git a/addon/defaults/preferences/defaults.js b/addon/prefs.js
similarity index 100%
rename from addon/defaults/preferences/defaults.js
rename to addon/prefs.js