diff --git a/src/file_ps.c b/src/file_ps.c
index 75293c08..1e29d1b5 100644
--- a/src/file_ps.c
+++ b/src/file_ps.c
@@ -33,9 +33,8 @@
 #include "common.h"
 
 
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_ps(file_stat_t *file_stat);
-static data_check_t data_check_ps(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery);
 
 const file_hint_t file_hint_ps= {
   .extension="ps",
@@ -49,12 +48,8 @@ const file_hint_t file_hint_ps= {
 static const unsigned char ps_header[11]= { '%','!','P','S','-','A','d','o','b','e','-'};
 
 /*@
-  @ requires \valid(file_recovery);
-  @ requires \valid(file_recovery->handle);
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \separated(file_recovery, file_recovery->handle, file_recovery->extension, &errno, &Frama_C_entropy_source);
-  @ ensures \valid(file_recovery->handle);
-  @ ensures valid_file_recovery(file_recovery);
+  @ requires valid_file_check_param(file_recovery);
+  @ ensures  valid_file_check_result(file_recovery);
   @ assigns *file_recovery->handle, errno, file_recovery->file_size;
   @ assigns Frama_C_entropy_source;
   @*/
@@ -66,13 +61,9 @@ static void file_check_ps(file_recovery_t *file_recovery)
 
 /*@
   @ requires buffer_size > 8;
-  @ requires (buffer_size&1)==0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires \valid(file_recovery);
   @ requires file_recovery->data_check==&data_check_ps;
-  @ requires file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE;
-  @ requires \separated(buffer, file_recovery);
-  @ ensures \result == DC_CONTINUE || \result == DC_STOP;
+  @ requires valid_data_check_param(buffer, buffer_size, file_recovery);
+  @ ensures  valid_data_check_result(\result, file_recovery);
   @ assigns file_recovery->calculated_file_size;
   @*/
 static data_check_t data_check_ps(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
@@ -94,14 +85,10 @@ static data_check_t data_check_ps(const unsigned char *buffer, const unsigned in
 }
 
 /*@
-  @ 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_ps, buffer+(..), 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;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
   @*/
 static int header_check_ps(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)
 {