--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -6639,17 +6639,17 @@ var WebappsUI = {
     });
   },
 
   get iconSize() {
     let iconSize = 64;
     try {
       Cu.import("resource://gre/modules/JNI.jsm");
       let jni = new JNI();
-      let cls = jni.findClass("org.mozilla.gecko.GeckoAppShell");
+      let cls = jni.findClass("org/mozilla/gecko/GeckoAppShell");
       let method = jni.getStaticMethodID(cls, "getPreferredIconSize", "()I");
       iconSize = jni.callStaticIntMethod(cls, method);
       jni.close();
     } catch(ex) {
       console.log(ex);
     }
 
     delete this.iconSize;

--- a/mobile/android/modules/JNI.jsm
+++ b/mobile/android/modules/JNI.jsm
@@ -1,13 +1,13 @@
 /* Very basic JNI support for JS
  *
  * Example Usage:
  *   let jni = new JNI();
- *   cls = jni.findClass("org.mozilla.gecko.GeckoAppShell");
+ *   cls = jni.findClass("org/mozilla/gecko/GeckoAppShell");
  *   method = jni.getStaticMethodID(cls, "getPreferredIconSize", "(I)I");
  *
  *   let val = jni.callStaticIntMethod(cls, method, 3);
  *   // close the jni library when you are done
  *   jni.close();
  */
 let EXPORTED_SYMBOLS = ["JNI"];