@@ -193,6 +193,10 @@ writebyte(Uint8 b)

 		fprintf(stderr, "-- Writing in zero-page: %02x\n", b);

 		return 0;

 	}

+	else if(p.ptr < p.length) {

+		fprintf(stderr, "-- Memory overwrite: %04x -> %04x\n", p.length, p.ptr);

+		return 0;

+	}

 	p.data[p.ptr++] = b;

 	p.length = p.ptr;

 	litlast = 0;

@@ -213,6 +217,7 @@ writelitbyte(Uint8 b)

 	if(litlast) { /* combine literals */

 		Uint8 hb = p.data[p.ptr - 1];

 		p.ptr -= 2;

+		p.length = p.ptr;

 		return writeshort((hb << 8) + b, 1);

 	}

 	if(!writebyte(findopcode("LIT"))) return 0;