diff --git a/src/file_exs.c b/src/file_exs.c
index 355211ae..f7761b6f 100644
--- a/src/file_exs.c
+++ b/src/file_exs.c
@@ -31,7 +31,7 @@
 #include "types.h"
 #include "filegen.h"
 
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_exs(file_stat_t *file_stat);
 
 const file_hint_t file_hint_exs= {
@@ -44,9 +44,9 @@ const file_hint_t file_hint_exs= {
 };
 
 /*@
-  @ requires \valid(file_recovery);
-  @ requires valid_read_string((char*)&file_recovery->filename);
   @ requires file_recovery->file_rename==&file_rename_exs;
+  @ requires valid_file_rename_param(file_recovery);
+  @ ensures  valid_file_rename_result(file_recovery);
   @*/
 static void file_rename_exs(file_recovery_t *file_recovery)
 {
@@ -60,22 +60,13 @@ static void file_rename_exs(file_recovery_t *file_recovery)
   file_rename(file_recovery, buffer, buffer_size, 0x14, "exs", 0);
 }
 
-
 /*@
   @ requires buffer_size >= 0x14;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires \valid_read(file_recovery);
-  @ requires file_recovery->file_stat==\null || valid_read_string((char*)file_recovery->filename);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_exs, buffer+(..), file_recovery, file_recovery_new);
-  @ ensures \result == 0 || \result == 1;
-  @ ensures (\result == 1) ==> (file_recovery_new->file_stat == \null);
-  @ ensures (\result == 1) ==> (file_recovery_new->handle == \null);
-  @ ensures (\result == 1) ==> (file_recovery_new->file_rename == &file_rename_exs);
-  @ ensures (\result == 1) ==> (valid_read_string(file_recovery_new->extension));
-  @ ensures (\result == 1) ==> \separated(file_recovery_new, file_recovery_new->extension);
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
+  @ ensures  (\result == 1) ==> (file_recovery_new->file_rename == &file_rename_exs);
+  @ ensures  (\result == 1) ==> (valid_read_string(file_recovery_new->extension));
   @ assigns  *file_recovery_new;
   @*/
 static int header_check_exs(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)