diff --git a/python/obitools3/files/uncompress.pyx b/python/obitools3/files/uncompress.pyx
index 0de9180..59a1fd2 100644
--- a/python/obitools3/files/uncompress.pyx
+++ b/python/obitools3/files/uncompress.pyx
@@ -99,6 +99,8 @@ cdef class CompressedFile:
                 self.accessor = c(magic)
         
         if self.accessor is None:
+            if 'b' in magic.stream_mode:
+                magic.binary.seek(0)
             self.accessor = magic
         
         if ((hasattr(stream, 'headers') and