diff --git a/platform.h b/platform.h
index b299db7..4cbcca0 100644
--- a/platform.h
+++ b/platform.h
@@ -5,10 +5,6 @@
 /* configurable options */
 /* select your host type (or do it in the Makefile):
  * #define  UNIX_HOST
- * #define  FLYINGFOX_HOST
- * #define  SURVEYOR_HOST
- * #define  SRV1_UNIX_HOST
- * #define  UMON_HOST
  * #define  WIN32  (predefined on MSVC)
  */
 
@@ -55,11 +51,7 @@
 #   define BIG_ENDIAN
 #  endif
 # endif
-
-extern jmp_buf ExitBuf;
-
-#else
-# ifdef WIN32
+#elif defined(WIN32)
 #  define USE_MALLOC_STACK                   /* stack is allocated using malloc() */
 #  define USE_MALLOC_HEAP                    /* heap is allocated using malloc() */
 #  include <stdio.h>
@@ -74,74 +66,10 @@ extern jmp_buf ExitBuf;
 #  include <math.h>
 #  define PICOC_MATH_LIBRARY
 #  undef BIG_ENDIAN
+#else
+#error ***** A platform must be explicitly defined! *****
+#endif
 
 extern jmp_buf ExitBuf;
 
-# else
-#  ifdef FLYINGFOX_HOST
-#   define HEAP_SIZE (16*1024)               /* space for the heap and the stack */
-#   define NO_HASH_INCLUDE
-#   include <stdlib.h>
-#   include <ctype.h>
-#   include <string.h>
-#   include <sys/types.h>
-#   include <stdarg.h>
-#   include <setjmp.h>
-#   include <math.h>
-#   define assert(x)
-#   define BUILTIN_MINI_STDLIB
-#   undef BIG_ENDIAN
-
-#  else
-#   ifdef SURVEYOR_HOST
-#    define HEAP_SIZE C_HEAPSIZE
-#    define NO_FP
-#    define NO_CTYPE
-#    define NO_HASH_INCLUDE
-#    define NO_MODULUS
-#    include <cdefBF537.h>
-#    include "../string.h"
-#    include "../print.h"
-#    include "../srv.h"
-#    include "../setjmp.h"
-#    include "../stdarg.h"
-#    include "../colors.h"
-#    include "../neural.h"
-#    include "../gps.h"
-#    include "../i2c.h"
-#    include "../jpeg.h"
-#    include "../malloc.h"
-#    include "../xmodem.h"
-#    define assert(x)
-#    undef BIG_ENDIAN
-#    define NO_CALLOC
-#    define NO_REALLOC
-#    define BROKEN_FLOAT_CASTS
-#    define BUILTIN_MINI_STDLIB
-#   else
-#    ifdef UMON_HOST
-#     define HEAP_SIZE (128*1024)               /* space for the heap and the stack */
-#     define NO_FP
-#     define BUILTIN_MINI_STDLIB
-#     include <stdlib.h>
-#     include <string.h>
-#     include <ctype.h>
-#     include <sys/types.h>
-#     include <stdarg.h>
-#     include <math.h>
-#     include "monlib.h"
-#     define assert(x)
-#     define malloc mon_malloc
-#     define calloc(a,b) mon_malloc(a*b)
-#     define realloc mon_realloc
-#     define free mon_free
-#    endif
-#   endif
-#  endif
-
-extern int ExitBuf[];
-
-# endif
-#endif
-
 #endif /* PLATFORM_H */