diff --git a/src/buffer.c b/src/buffer.c
index 57fe813a..6f96c2fa 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -402,10 +402,12 @@ check_compressed_archive (bool *pshort)
   /* Restore global values */
   read_full_records = sfr;
 
-  if ((strcmp (record_start->header.magic, TMAGIC) == 0 ||
-       strcmp (record_start->buffer + offsetof (struct posix_header, magic),
-	       OLDGNU_MAGIC) == 0) &&
-      tar_checksum (record_start, true) == HEADER_SUCCESS)
+  if (record_start != record_end /* no files smaller than BLOCKSIZE */
+      && (strcmp (record_start->header.magic, TMAGIC) == 0
+          || strcmp (record_start->buffer + offsetof (struct posix_header,
+                                                      magic),
+                     OLDGNU_MAGIC) == 0)
+      && tar_checksum (record_start, true) == HEADER_SUCCESS)
     /* Probably a valid header */
     return ct_tar;