diff --git a/tmk_core/common/progmem.h b/tmk_core/common/progmem.h
index 39a918fe9..41b5b537c 100644
--- a/tmk_core/common/progmem.h
+++ b/tmk_core/common/progmem.h
@@ -4,6 +4,7 @@
 #    include <avr/pgmspace.h>
 #else
 #    define PROGMEM
+#    define PGM_P const char *
 #    define memcpy_P(dest, src, n) memcpy(dest, src, n)
 #    define pgm_read_byte(address_short) *((uint8_t*)(address_short))
 #    define pgm_read_word(address_short) *((uint16_t*)(address_short))
diff --git a/tmk_core/protocol/lufa/adafruit_ble.h b/tmk_core/protocol/lufa/adafruit_ble.h
index cef46fe9f..aebded7b3 100644
--- a/tmk_core/protocol/lufa/adafruit_ble.h
+++ b/tmk_core/protocol/lufa/adafruit_ble.h
@@ -2,18 +2,19 @@
  * Author: Wez Furlong, 2016
  * Supports the Adafruit BLE board built around the nRF51822 chip.
  */
+
 #pragma once
-#ifdef MODULE_ADAFRUIT_BLE
-#    include <stdbool.h>
-#    include <stdint.h>
-#    include <string.h>
 
-#    include "config_common.h"
-#    include "progmem.h"
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
 
-#    ifdef __cplusplus
+#include "config_common.h"
+#include "progmem.h"
+
+#ifdef __cplusplus
 extern "C" {
-#    endif
+#endif
 
 /* Instruct the module to enable HID keyboard support and reset */
 extern bool adafruit_ble_enable_keyboard(void);
@@ -54,8 +55,6 @@ extern uint32_t adafruit_ble_read_battery_voltage(void);
 extern bool adafruit_ble_set_mode_leds(bool on);
 extern bool adafruit_ble_set_power_level(int8_t level);
 
-#    ifdef __cplusplus
+#ifdef __cplusplus
 }
-#    endif
-
-#endif  // MODULE_ADAFRUIT_BLE
+#endif
diff --git a/tmk_core/protocol/lufa/outputselect.c b/tmk_core/protocol/lufa/outputselect.c
index b115ea969..f758c6528 100644
--- a/tmk_core/protocol/lufa/outputselect.c
+++ b/tmk_core/protocol/lufa/outputselect.c
@@ -12,8 +12,12 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include "lufa.h"
 #include "outputselect.h"
+
+#if defined(PROTOCOL_LUFA)
+#    include "lufa.h"
+#endif
+
 #ifdef MODULE_ADAFRUIT_BLE
 #    include "adafruit_ble.h"
 #endif
@@ -35,12 +39,18 @@ void set_output(uint8_t output) {
  */
 __attribute__((weak)) void set_output_user(uint8_t output) {}
 
+static bool is_usb_configured(void) {
+#if defined(PROTOCOL_LUFA)
+    return USB_DeviceState == DEVICE_STATE_Configured;
+#endif
+}
+
 /** \brief Auto Detect Output
  *
  * FIXME: Needs doc
  */
 uint8_t auto_detect_output(void) {
-    if (USB_DeviceState == DEVICE_STATE_Configured) {
+    if (is_usb_configured()) {
         return OUTPUT_USB;
     }
 
diff --git a/tmk_core/protocol/lufa/outputselect.h b/tmk_core/protocol/lufa/outputselect.h
index 24fe4daa2..7f7ed00b9 100644
--- a/tmk_core/protocol/lufa/outputselect.h
+++ b/tmk_core/protocol/lufa/outputselect.h
@@ -12,6 +12,10 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#pragma once
+
+#include <stdint.h>
+
 enum outputs {
     OUTPUT_AUTO,
 
@@ -37,4 +41,4 @@ enum outputs {
 void    set_output(uint8_t output);
 void    set_output_user(uint8_t output);
 uint8_t auto_detect_output(void);
-uint8_t where_to_send(void);
\ No newline at end of file
+uint8_t where_to_send(void);
diff --git a/tmk_core/protocol/serial.h b/tmk_core/protocol/serial.h
index 93ac99898..b70d117d7 100644
--- a/tmk_core/protocol/serial.h
+++ b/tmk_core/protocol/serial.h
@@ -35,13 +35,10 @@ ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.
 */
 
-#ifndef SERIAL_H
-#define SERIAL_H
+#pragma once
 
 /* host role */
 void    serial_init(void);
 uint8_t serial_recv(void);
 int16_t serial_recv2(void);
 void    serial_send(uint8_t data);
-
-#endif