diff --git a/src/file_asf.c b/src/file_asf.c
index 8f9fbd40..b3939e48 100644
--- a/src/file_asf.c
+++ b/src/file_asf.c
@@ -44,13 +44,6 @@ const file_hint_t file_hint_asf= {
   .register_header_check=&register_header_check_asf
 };
 
-static const unsigned char asf_header[4]= { 0x30,0x26,0xB2,0x75};
-
-static void register_header_check_asf(file_stat_t *file_stat)
-{
-  register_header_check(0, asf_header,sizeof(asf_header), &header_check_asf, file_stat);
-}
-
 struct asf_header_obj_s {
   unsigned char object_id[16];
   uint64_t	object_size;
@@ -69,45 +62,43 @@ struct asf_file_prop_s {
 
 static int header_check_asf(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)
 {
-  static const unsigned char asf_header_id[16]= {
+  const struct asf_header_obj_s *asf_header_obj=(const struct asf_header_obj_s *)buffer;
+  const struct asf_file_prop_s  *asf_file_prop=(const struct asf_file_prop_s*)(buffer+le64(asf_header_obj->object_size));
+  unsigned int i;
+  if(le64(asf_header_obj->object_size)<30 ||
+      le64(asf_header_obj->object_size)>buffer_size)
+    return 0;
+  reset_file_recovery(file_recovery_new);
+  file_recovery_new->extension=file_hint_asf.extension;
+  for(i=0;
+      i<le32(asf_header_obj->nbr_header_obj) &&
+      (const unsigned char *)(asf_file_prop+1) < buffer + buffer_size;
+      i++)
+  {
+    static const unsigned char asf_file_prop_id[16]= {
+      0xa1, 0xdc, 0xab, 0x8c, 0x47, 0xa9, 0xcf, 0x11, 
+      0x8e, 0xe4, 0x00, 0xc0, 0x0c, 0x20, 0x53, 0x65
+    };
+    if(memcmp(asf_file_prop->object_id, asf_file_prop_id, sizeof(asf_file_prop_id))==0)
+    {
+      file_recovery_new->calculated_file_size=le64(asf_file_prop->file_size);
+      file_recovery_new->data_check=&data_check_size;
+      file_recovery_new->file_check=&file_check_size;
+      return 1;
+    }
+    if( le64(asf_file_prop->object_size)==0 ||
+	le64(asf_file_prop->object_size)>1024*1024)
+      return 1;
+    asf_file_prop=(const struct asf_file_prop_s *)((const char *)asf_file_prop + le64(asf_file_prop->object_size));
+  }
+  return 1;
+}
+
+static void register_header_check_asf(file_stat_t *file_stat)
+{
+  static const unsigned char asf_header[16]= {
     0x30, 0x26, 0xb2, 0x75, 0x8e, 0x66, 0xcf, 0x11, 
     0xa6, 0xd9, 0x00, 0xaa, 0x00, 0x62, 0xce, 0x6c
   };
-  if(memcmp(buffer, asf_header_id, sizeof(asf_header_id))==0)
-  {
-    unsigned int i;
-    const struct asf_header_obj_s *asf_header_obj=(const struct asf_header_obj_s *)buffer;
-    const struct asf_file_prop_s  *asf_file_prop=(const struct asf_file_prop_s*)(asf_header_obj+1);
-    reset_file_recovery(file_recovery_new);
-    file_recovery_new->extension=file_hint_asf.extension;
-    for(i=0;
-	i<le32(asf_header_obj->nbr_header_obj) &&
-	(const unsigned char *)(asf_file_prop+1) < buffer + buffer_size;
-	i++)
-    {
-      static const unsigned char asf_file_prop_id[16]= {
-	0xa1, 0xdc, 0xab, 0x8c, 0x47, 0xa9, 0xcf, 0x11, 
-	0x8e, 0xe4, 0x00, 0xc0, 0x0c, 0x20, 0x53, 0x65
-      };
-      if(memcmp(asf_file_prop->object_id, asf_file_prop_id, sizeof(asf_file_prop_id))==0)
-      {
-	file_recovery_new->calculated_file_size=le64(asf_file_prop->file_size);
-	file_recovery_new->data_check=&data_check_size;
-	file_recovery_new->file_check=&file_check_size;
-	return 1;
-      }
-      if( le64(asf_file_prop->object_size)==0 ||
-	  le64(asf_file_prop->object_size)>1024*1024)
-	return 1;
-      asf_file_prop=(const struct asf_file_prop_s *)((const char *)asf_file_prop + le64(asf_file_prop->object_size));
-    }
-    return 1;
-  }
-  if(memcmp(buffer, asf_header, sizeof(asf_header))==0)
-  {
-    reset_file_recovery(file_recovery_new);
-    file_recovery_new->extension=file_hint_asf.extension;
-    return 1;
-  }
-  return 0;
+  register_header_check(0, asf_header,sizeof(asf_header), &header_check_asf, file_stat);
 }