diff --git a/f256lib/f256.c b/f256lib/f256.c
index bc9d2bf..83d61f2 100644
--- a/f256lib/f256.c
+++ b/f256lib/f256.c
@@ -165,3 +165,15 @@ void FAR_POKEW(uint32_t address, uint16_t value) {
 
 	SWAP_IO_SHUTDOWN();
 }
+
+
+#ifndef WITHOUT_MAIN
+#ifdef main
+#undef main
+#endif
+int f256main(int argc, char *argv[]);
+int main(void) {
+	f256Init();
+	return f256main(kernelArgs->common.extlen / 2, (char **)kernelArgs->common.ext);
+}
+#endif
diff --git a/f256lib/f256.h b/f256lib/f256.h
index 2d1f4d1..a586d7f 100644
--- a/f256lib/f256.h
+++ b/f256lib/f256.h
@@ -154,7 +154,7 @@ typedef struct colorS {
 #define SET_BIT(x, pos)     (x |= (1U << pos))
 
 
-// Work out configuration DEFINEs.
+// Verify configuration DEFINEs.
 #ifdef WITHOUT_GRAPHICS
 #define WITHOUT_BITMAP
 #define WITHOUT_TILE
@@ -162,16 +162,29 @@ typedef struct colorS {
 #endif
 
 #ifndef WITHOUT_FILE   // File requires Kernel
-#undef WITHOUT_KERNEL
+#ifdef WITHOUT_KERNEL
+#error "FILE requires KERNEL."
+#endif
 #endif
 
 #ifndef WITHOUT_TEXT   // Text requries Math
-#undef WITHOUT_MATH
+#ifdef WITHOUT_MATH
+#error "TEXT requires MATH."
+#endif
 #endif
 
 #ifndef WITHOUT_BITMAP // Bitmap requries Math
-#undef WITHOUT_MATH
+#ifdef WITHOUT_MATH
+#error "BITMAP requires MATH."
 #endif
+#endif
+
+#ifndef WITHOUT_MAIN   // Main requries Kernel
+#ifdef WITHOUT_KERNEL
+#error "MAIN requires KERNEL."
+#endif
+#endif
+
 
 #ifndef WITHOUT_KERNEL
 #include "kernel.h"
@@ -215,6 +228,11 @@ void     FAR_POKE(uint32_t address, byte value);
 void     FAR_POKEW(uint32_t address, uint16_t value);
 
 
+#ifndef WITHOUT_MAIN
+#define main f256main
+#endif
+
+
 #ifdef __cplusplus
 }
 #endif