diff --git a/gfxconf.example.h b/gfxconf.example.h
index 66411ec3..686f4473 100644
--- a/gfxconf.example.h
+++ b/gfxconf.example.h
@@ -26,13 +26,16 @@
 ///////////////////////////////////////////////////////////////////////////
 // GOS - One of these must be defined, preferably in your Makefile       //
 ///////////////////////////////////////////////////////////////////////////
-//#define GFX_USE_OS_RAW32                             FALSE
 //#define GFX_USE_OS_CHIBIOS                           FALSE
 //#define GFX_USE_OS_FREERTOS                          FALSE
 //    #define GFX_FREERTOS_USE_TRACE                   FALSE
 //#define GFX_USE_OS_WIN32                             FALSE
 //#define GFX_USE_OS_LINUX                             FALSE
 //#define GFX_USE_OS_OSX                               FALSE
+//#define GFX_USE_OS_RAW32                             FALSE
+//    #define GOS_RAW_HEAP_SIZE                        0
+//    #define INTERRUPTS_OFF()                         optional_code
+//    #define INTERRUPTS_ON()                          optional_code
 
 
 ///////////////////////////////////////////////////////////////////////////
diff --git a/src/gos/sys_options.h b/src/gos/sys_options.h
index cfbed057..c7376878 100644
--- a/src/gos/sys_options.h
+++ b/src/gos/sys_options.h
@@ -75,6 +75,19 @@
  	#ifndef GFX_FREERTOS_USE_TRACE
  		#define GFX_FREERTOS_USE_TRACE	FALSE
  	#endif
+ 	/**
+ 	 * @brief	How much RAM should uGFX use for the heap
+ 	 * @details	Defaults to 0. Only valid with GFX_USE_OS_RAW32
+ 	 * @note	If 0 then the standard C runtime malloc(), free() and realloc()
+ 	 * 			are used.
+ 	 * @note	If it is non-zero then this is the number of bytes of RAM
+ 	 * 			to use for the heap (gfxAlloc() and gfxFree()). No C
+ 	 * 			runtime routines will be used and a new routine @p gfxAddHeapBlock()
+ 	 * 			is added allowing the user to add extra memory blocks to the heap.
+ 	 */
+	#ifndef GOS_RAW_HEAP_SIZE
+		#define GOS_RAW_HEAP_SIZE		0
+	#endif
 /** @} */
 
 #endif /* _GOS_OPTIONS_H */