diff --git a/README.markdown b/README.markdown
index 100ad9b..6e79b9d 100644
--- a/README.markdown
+++ b/README.markdown
@@ -12,7 +12,7 @@ Structure
 
 * This folder
   * Open Access Control folder
-    * Open Access Control.pde (Arduino code -- open from the Arduino IDE.)
+    * Open Access Control.ino (Arduino code -- open from the Arduino IDE.)
   * libraries folder (copy the contents of this folder to your Arduino program's libraries folder and restart the Arduino program.)
     * ShiftLCD folder
       * keywords.txt