diff --git a/atahpt.c b/atahpt.c
index 2bf4a11..de888b0 100644
--- a/atahpt.c
+++ b/atahpt.c
@@ -18,6 +18,8 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
+#if defined(__i386__) || defined(__x86_64__)
+
 #include <stdlib.h>
 #include <string.h>
 #include "flash.h"
@@ -77,3 +79,7 @@
 	OUTL((uint32_t)addr, io_base_addr + BIOS_ROM_ADDR);
 	return INB(io_base_addr + BIOS_ROM_DATA);
 }
+
+#else
+#error PCI port I/O access is not supported on this architecture yet.
+#endif