diff --git a/libs/microbit/control.cpp b/libs/microbit/control.cpp
index 7556c3ae..2d8cc1f5 100644
--- a/libs/microbit/control.cpp
+++ b/libs/microbit/control.cpp
@@ -163,4 +163,12 @@ namespace control {
     StringData* deviceName() {
         return ManagedString(microbit_friendly_name()).leakData();        
     }
+    
+    /**
+    * Derive a unique, consistent serial number of this device from internal data.
+    */
+    //%
+    int deviceSerialNumber() {
+        return microbit_serial_number();
+    }
 }