diff --git a/FlippR-Driver/src/output/factories/LampFactory.cpp b/FlippR-Driver/src/output/factories/LampFactory.cpp
index 34c76bd..dc0bf0b 100644
--- a/FlippR-Driver/src/output/factories/LampFactory.cpp
+++ b/FlippR-Driver/src/output/factories/LampFactory.cpp
@@ -73,9 +73,9 @@ void LampFactory::set_mux_pins()
 
   std::array<uint8_t, 13> pins;
 
-  for(int i = 1; i < 14; i++)
+  for(char i = 1; i < 14; i++)
   {
-    pins.at(i) = this->get_address_pin(address_pins.at("E" + (char) i));
+    pins.at(i-1) = this->get_address_pin(address_pins.at("E" + std::to_string(i)));
   }
 
   std::dynamic_pointer_cast<detail::DriverBoardPinController>(this->pin_controller)->set_mux_pins(pins);