diff --git a/config.gen3.h b/config.gen3.h
index 6be84c2..18530d8 100644
--- a/config.gen3.h
+++ b/config.gen3.h
@@ -1,3 +1,6 @@
+#ifndef	_CONFIG_H
+#define	_CONFIG_H
+
 /*
 	CONTENTS
 	
@@ -419,3 +422,5 @@ DEFINE_TEMP_SENSOR(noheater,	TT_INTERCOM,		0)
 * OCR5CL - PL5 - DIO44                                                      *
 *                                                                           *
 \***************************************************************************/
+
+#endif /* _CONFIG_H */
diff --git a/config.gen6.h b/config.gen6.h
index ee6ef15..415a839 100644
--- a/config.gen6.h
+++ b/config.gen6.h
@@ -1,3 +1,6 @@
+#ifndef	_CONFIG_H
+#define	_CONFIG_H
+
 /*
   Sample configuration file for the GEN6-Board sold by Camiel Gubbels.
   http://www.reprap.org/wiki/Generation_6_Electronics
@@ -408,3 +411,5 @@ DEFINE_HEATER(extruder,   PORTD, PIND6, OCR2B)
 * OCR5CL - PL5 - DIO44                                                      *
 *                                                                           *
 \***************************************************************************/
+
+#endif /* _CONFIG_H */
diff --git a/config.h.dist b/config.h.dist
index 999cec9..7c0ea11 100644
--- a/config.h.dist
+++ b/config.h.dist
@@ -1,3 +1,6 @@
+#ifndef	_CONFIG_H
+#define	_CONFIG_H
+
 /*
 	CONTENTS
 	
@@ -436,3 +439,5 @@ DEFINE_HEATER(bed,			PORTB, PINB4, OCR0B)
 * OCR5CL - PL5 - DIO44                                                      *
 *                                                                           *
 \***************************************************************************/
+
+#endif /* _CONFIG_H */
diff --git a/config.ramps.h b/config.ramps.h
index 9223c5f..70107be 100644
--- a/config.ramps.h
+++ b/config.ramps.h
@@ -1,3 +1,6 @@
+#ifndef	_CONFIG_H
+#define	_CONFIG_H
+
 /*
 	CONTENTS
 	
@@ -422,3 +425,5 @@ DEFINE_HEATER(fan,			PORTH, PINH6, OCR2B)
 * OCR5CL - PL5 - DIO44                                                      *
 *                                                                           *
 \***************************************************************************/
+
+#endif /* _CONFIG_H */