diff --git a/extruder/config.h.dist b/extruder/config.h.dist
index fa90030..18251b0 100644
--- a/extruder/config.h.dist
+++ b/extruder/config.h.dist
@@ -1,5 +1,4 @@
-#ifndef	_CONFIG_H
-#define	_CONFIG_H
+/* Notice to developers: this file is intentionally included twice. */
 
 /*
 	CPU clock rate
@@ -94,5 +93,3 @@ DEFINE_HEATER(bed,			AIO1)
 
 #define enable_motors()				do { TCCR0A |= MASK(COM0A1) | MASK(COM0B1); } while (0)
 #define disable_motors()			do { TCCR0A &= ~MASK(COM0A1) & ~MASK(COM0B1); } while (0)
-
-#endif	/* _CONFIG_H */
diff --git a/extruder/heater.h b/extruder/heater.h
index 41af518..61486e6 100644
--- a/extruder/heater.h
+++ b/extruder/heater.h
@@ -9,7 +9,6 @@
 #define	disable_heater()	heater_set(0, 0)
 
 #undef DEFINE_HEATER
-#undef _CONFIG_H
 #define DEFINE_HEATER(name, pin) HEATER_ ## name,
 typedef enum
 {
diff --git a/extruder/temp.h b/extruder/temp.h
index 5e56038..6a1d5e5 100644
--- a/extruder/temp.h
+++ b/extruder/temp.h
@@ -13,7 +13,6 @@ we still need to specify which analog pins we use in machine.h for the analog se
 */
 
 #undef DEFINE_TEMP_SENSOR
-#undef _CONFIG_H
 #define DEFINE_TEMP_SENSOR(name, type, pin) TEMP_SENSOR_ ## name,
 typedef enum {
 	#include "config.h"
diff --git a/heater.h b/heater.h
index 41af518..61486e6 100644
--- a/heater.h
+++ b/heater.h
@@ -9,7 +9,6 @@
 #define	disable_heater()	heater_set(0, 0)
 
 #undef DEFINE_HEATER
-#undef _CONFIG_H
 #define DEFINE_HEATER(name, pin) HEATER_ ## name,
 typedef enum
 {
diff --git a/temp.h b/temp.h
index 5e56038..6a1d5e5 100644
--- a/temp.h
+++ b/temp.h
@@ -13,7 +13,6 @@ we still need to specify which analog pins we use in machine.h for the analog se
 */
 
 #undef DEFINE_TEMP_SENSOR
-#undef _CONFIG_H
 #define DEFINE_TEMP_SENSOR(name, type, pin) TEMP_SENSOR_ ## name,
 typedef enum {
 	#include "config.h"