diff --git a/src/file_snag.c b/src/file_snag.c
index db571362..c9797b6a 100644
--- a/src/file_snag.c
+++ b/src/file_snag.c
@@ -32,7 +32,7 @@
 #include "filegen.h"
 #include "file_doc.h"
 
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_snag(file_stat_t *file_stat);
 
 const file_hint_t file_hint_snag= {
@@ -45,12 +45,9 @@ const file_hint_t file_hint_snag= {
 };
 
 /*@
-  @ requires \valid(file_recovery);
-  @ requires \valid(file_recovery->handle);
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \separated(file_recovery, file_recovery->handle);
   @ requires file_recovery->file_check == &file_check_snag;
-  @ ensures \valid(file_recovery->handle);
+  @ requires valid_file_check_param(file_recovery);
+  @ ensures  valid_file_check_result(file_recovery);
   @*/
 static void file_check_snag(file_recovery_t *file_recovery)
 {
@@ -58,13 +55,9 @@ static void file_check_snag(file_recovery_t *file_recovery)
 }
 
 /*@
-  @ 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_snag, 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_snag(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)