Index: game.c
==================================================================
--- game.c
+++ game.c
@@ -42,26 +42,38 @@
 static size_t dum_size; // not used by Free Hero Mesh, but needed by some C library functions.
 
 int encode_move(FILE*fp,MoveItem v) {
   // Encodes a single move and writes the encoded move to the file.
   // Returns the number of bytes of the encoded move.
-  fputc(v,fp);
-  return 1;
+  if(v>=8 && v<256) {
+    fputc(v,fp);
+    return 1;
+  } else {
+    fatal("Unencodable move (%u)\n",(int)v);
+  }
 }
 
 int encode_move_list(FILE*fp) {
   // Encodes the current replay list into the file; returns the number of bytes.
   // Does not write a null terminator.
-  fwrite(replay_list,1,replay_count,fp);
-  return replay_count;
+  int i;
+  int c=0;
+  for(i=0;i<replay_count;i++) c+=encode_move(fp,replay_list[i]);
+  return c;
 }
 
 MoveItem decode_move(FILE*fp) {
   // Decodes a single move from the file, and returns the move.
   // Returns zero if there is no more moves.
   int v=fgetc(fp);
-  return (v==EOF?0:v);
+  if(v>=8 && v<256) {
+    return v;
+  } else if(v==EOF || !v) {
+    return 0;
+  } else {
+    fatal("Undecodable move (%u)\n",v);
+  }
 }
 
 int decode_move_list(FILE*fp) {
   // Decodes a move list from the file, and stores it in replay_list and replay_count.
   // Returns the number of moves (replay_count).

Index: heromesh.h
==================================================================
--- heromesh.h
+++ heromesh.h
@@ -318,11 +318,11 @@
 const char*init_level(void);
 void swap_world(void);
 
 // == game ==
 
-typedef Uint8 MoveItem;
+typedef Uint16 MoveItem;
 
 extern MoveItem*replay_list;
 extern size_t replay_size;
 extern Uint16 replay_count,replay_pos,replay_mark;
 extern Uint8 solution_replay;