diff --git a/src/file_dex.c b/src/file_dex.c
index 3c1b2298..0190be56 100644
--- a/src/file_dex.c
+++ b/src/file_dex.c
@@ -33,6 +33,7 @@
 #include "filegen.h"
 #include "common.h"
 
+/*@ requires \valid(file_stat); */
 static void register_header_check_dex(file_stat_t *file_stat);
 
 const file_hint_t file_hint_dex= {
@@ -72,6 +73,17 @@ struct dex_header
   uint32_t	data_off;
 } __attribute__ ((gcc_struct, __packed__));
 
+/*@
+  @ requires buffer_size >= sizeof(struct dex_header);
+  @ 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_dex, buffer+(..), file_recovery, file_recovery_new);
+  @ assigns  *file_recovery_new;
+  @ ensures \result == 0 || \result == 1;
+  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
+  @*/
 static int header_check_dex(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)
 {
   const struct dex_header *dex=(const struct dex_header*)buffer;