diff --git a/config_wrapper.h b/config_wrapper.h
index f52193e..137957b 100644
--- a/config_wrapper.h
+++ b/config_wrapper.h
@@ -7,10 +7,23 @@
 */
 #include "arduino.h"
 
-#ifndef DEFINE_HEATER
-  #define DEFINE_HEATER(...)
+#ifndef DEFINE_HEATER_ACTUAL
+  #define DEFINE_HEATER_ACTUAL(...)
 #endif
 
+// Heater definition helpers.  This collection of macros turns any DEFINE_HEATER(...) macro
+// expansion into a DEFINE_HEATER_ACTUAL(a,b,c,d), i.e. a macro with four arguments.  Currently
+// we expand 3 to 6 arguments, but we ignore the 6th arg in this code.  This allows
+// us to use this "old" code with some "newer" configs which come at us from the future, so long
+// as the newer configs add parameters at the end of the list rather than in the middle.
+// From http://stackoverflow.com/questions/11761703/overloading-macro-on-number-of-arguments
+#define GET_MACRO(_1, _2, _3, _4, _5, _6, NAME, ...) NAME
+#define DEFINE_HEATER(...) GET_MACRO(__VA_ARGS__, DHTR_6, DHTR_5, DHTR_4, DHTR_3)(__VA_ARGS__)
+#define DHTR_3(name, pin, pwm) DEFINE_HEATER_ACTUAL(name, pin, 0, pwm, 100)
+#define DHTR_4(name, pin, invert, pwm) DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, 100)
+#define DHTR_5(name, pin, invert, pwm, max_pwm)  DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, max_pwm)
+#define DHTR_6(name, pin, invert, pwm, max_pwm, arg6)  DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, max_pwm)
+
 /**
   This wrapper config header is used to allow makefiles and test scripts to
   replace or augment the user's 'config.h' file in a controlled manner. A
diff --git a/heater-avr.c b/heater-avr.c
index 7bc8a0d..aa09664 100644
--- a/heater-avr.c
+++ b/heater-avr.c
@@ -32,9 +32,9 @@ typedef struct {
   #define HEATER_MAX_VALUE(dummy)
 #endif
 
-#undef DEFINE_HEATER
+#undef DEFINE_HEATER_ACTUAL
 /// \brief helper macro to fill heater definition struct from config.h
-#define	DEFINE_HEATER(name, pin, invert, pwm, max_value) { \
+#define DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, max_value) { \
   &(pin ## _WPORT), \
   pin ## _PIN, \
   invert ? 1 : 0, \
@@ -45,7 +45,7 @@ static const heater_definition_t heaters[NUM_HEATERS] =
 {
 	#include	"config_wrapper.h"
 };
-#undef DEFINE_HEATER
+#undef DEFINE_HEATER_ACTUAL
 
 
 /// \brief initialise heater subsystem
@@ -208,12 +208,12 @@ void heater_init() {
 	}
 
 	// set all heater pins to output
-  #undef DEFINE_HEATER
-  #define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
+  #undef DEFINE_HEATER_ACTUAL
+  #define DEFINE_HEATER_ACTUAL(name, pin, invert, ...) \
     SET_OUTPUT(pin);                            \
     WRITE(pin, invert ? 1 : 0);
   #include "config_wrapper.h"
-  #undef DEFINE_HEATER
+  #undef DEFINE_HEATER_ACTUAL
 
   pid_init();
 }
diff --git a/heater-lpc.c b/heater-lpc.c
index 46736d0..2b1fd30 100644
--- a/heater-lpc.c
+++ b/heater-lpc.c
@@ -83,8 +83,8 @@ typedef struct {
   #define HEATER_MAX_VALUE(dummy)
 #endif
 
-#undef DEFINE_HEATER
-#define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
+#undef DEFINE_HEATER_ACTUAL
+#define DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, max_value) \
   { \
     { pwm && pin ## _TIMER ? \
       &(pin ## _TIMER->MR[pin ## _MATCH]) : \
@@ -96,7 +96,7 @@ typedef struct {
 static const heater_definition_t heaters[NUM_HEATERS] = {
   #include "config_wrapper.h"
 };
-#undef DEFINE_HEATER
+#undef DEFINE_HEATER_ACTUAL
 
 /** Initialise heater subsystem.
 
@@ -143,8 +143,8 @@ void heater_init() {
       PIO1_9   CT16B1_MAT0     0x1            ---
   */
   // Auto-generate pin setup.
-  #undef DEFINE_HEATER
-  #define DEFINE_HEATER(name, pin, invert, pwm, max_value) \
+  #undef DEFINE_HEATER_ACTUAL
+  #define DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, max_value) \
     if (pwm && pin ## _TIMER) {                                             \
       uint32_t freq;                                                        \
                                                                             \
@@ -184,7 +184,7 @@ void heater_init() {
       WRITE(pin, invert ? 1 : 0);                                           \
     }
   #include "config_wrapper.h"
-  #undef DEFINE_HEATER
+  #undef DEFINE_HEATER_ACTUAL
 
   pid_init();
 }
diff --git a/heater-stm32.c b/heater-stm32.c
index 81aad6c..5551c5c 100644
--- a/heater-stm32.c
+++ b/heater-stm32.c
@@ -71,8 +71,8 @@ typedef struct {
   uint8_t uses_pwm;
 } heater_definition_t;
 
-#undef DEFINE_HEATER
-#define DEFINE_HEATER(name, pin, invert, pwm) \
+#undef DEFINE_HEATER_ACTUAL
+#define DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, ...) \
   { \
     { pwm && pin ## _TIMER ? \
       &(pin ## _TIMER-> EXPANDER(CCR, pin ## _CHANNEL,)) : \
@@ -83,7 +83,7 @@ typedef struct {
 static const heater_definition_t heaters[NUM_HEATERS] = {
   #include "config_wrapper.h"
 };
-#undef DEFINE_HEATER
+#undef DEFINE_HEATER_ACTUAL
 
 /** Initialise heater subsystem.
 
@@ -154,8 +154,8 @@ void heater_init() {
       
   */
   // Auto-generate pin setup.
-  #undef DEFINE_HEATER 
-  #define DEFINE_HEATER(name, pin, invert, pwm) \
+  #undef DEFINE_HEATER_ACTUAL 
+  #define DEFINE_HEATER_ACTUAL(name, pin, invert, pwm, ...) \
     if (pwm && pin ## _TIMER) {                                                          \
       uint32_t freq;                                                                     \
       uint8_t macro_mask;                                                                \
@@ -208,7 +208,7 @@ void heater_init() {
     }
 
     #include "config_wrapper.h"
-    #undef DEFINE_HEATER
+    #undef DEFINE_HEATER_ACTUAL
 
   pid_init();
 }
diff --git a/heater.h b/heater.h
index c78af97..da5b29a 100644
--- a/heater.h
+++ b/heater.h
@@ -29,15 +29,15 @@
 #endif
 
 
-#undef DEFINE_HEATER
-#define DEFINE_HEATER(name, pin, invert, pwm, ...) HEATER_ ## name,
+#undef DEFINE_HEATER_ACTUAL
+#define DEFINE_HEATER_ACTUAL(name, ...) HEATER_ ## name,
 typedef enum
 {
 	#include "config_wrapper.h"
 	NUM_HEATERS,
 	HEATER_noheater
 } heater_t;
-#undef DEFINE_HEATER
+#undef DEFINE_HEATER_ACTUAL
 
 /** This struct holds the runtime heater data.