diff --git a/src/file_wks.c b/src/file_wks.c
index 2159a346..5ef34287 100644
--- a/src/file_wks.c
+++ b/src/file_wks.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_wks(file_stat_t *file_stat);
 
 const file_hint_t file_hint_wks = {
@@ -55,13 +55,9 @@ const file_hint_t file_hint_wks = {
  * http://www.schnarff.com/file-formats/lotus-1-2-3/WSFF2.TXT
  */
 /*@
-  @ requires buffer_size > 0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_wks, buffer+(..), file_recovery, file_recovery_new);
-  @ 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);
   @ assigns  *file_recovery_new;
   @*/
 static int header_check_wk4(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)
@@ -72,13 +68,9 @@ static int header_check_wk4(const unsigned char *buffer, const unsigned int buff
 }
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
   @ requires separation: \separated(&file_hint_wks, buffer+(..), file_recovery, file_recovery_new);
-  @ 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);
   @ assigns  *file_recovery_new;
   @*/
 static int header_check_wks(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)