diff --git a/include/aio.h b/include/aio.h
index aff1e00939..b323e01b37 100644
--- a/include/aio.h
+++ b/include/aio.h
@@ -125,7 +125,11 @@ struct aiocb
   FAR volatile void *aio_buf;    /* Location of buffer */
   off_t aio_offset;              /* File offset */
   size_t aio_nbytes;             /* Length of transfer */
+#if CONFIG_NFILE_DESCRIPTORS > 127
   int16_t aio_fildes;            /* File descriptor (should be int) */
+#else
+  int8_t aio_fildes;             /* File descriptor (should be int) */
+#endif
   int8_t aio_reqprio;            /* Request priority offset (not used, should be int) */
   uint8_t aio_lio_opcode;        /* Operation to be performed (should be int) */