diff --git a/src/file_lso.c b/src/file_lso.c
index 2fd3e808..d553cbdd 100644
--- a/src/file_lso.c
+++ b/src/file_lso.c
@@ -31,6 +31,7 @@
 #include "types.h"
 #include "filegen.h"
 
+/*@ requires \valid(file_stat); */
 static void register_header_check_lso(file_stat_t *file_stat);
 
 const file_hint_t file_hint_lso= {
@@ -42,12 +43,34 @@ const file_hint_t file_hint_lso= {
   .register_header_check=&register_header_check_lso
 };
 
+/*@
+  @ requires valid_file_recovery(file_recovery);
+  @ requires \valid(file_recovery->handle);
+  @ requires \separated(file_recovery, file_recovery->handle, file_recovery->extension, &errno, &Frama_C_entropy_source);
+  @
+  @ requires file_recovery->file_check == &file_check_lso;
+  @ assigns *file_recovery->handle, errno, file_recovery->file_size;
+  @ assigns Frama_C_entropy_source;
+  @
+  @ ensures \valid(file_recovery->handle);
+  @*/
 static void file_check_lso(file_recovery_t *file_recovery)
 {
   const unsigned char lso_footer[6]= {0xFF, 0xFF, 0xFF, 0x7F, 0x7F, 0x7F};
   file_search_footer(file_recovery, lso_footer, sizeof(lso_footer), 0x46);
 }
 
+/*@
+  @ 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_lso, buffer+(..), file_recovery, file_recovery_new);
+  @ ensures  \result == 0 || \result == 1;
+  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
+  @ assigns  *file_recovery_new;
+  @*/
 static int header_check_lso(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)
 {
   reset_file_recovery(file_recovery_new);