diff --git a/include/linux/io.h b/include/linux/io.h
index 986f2bf..04cce4d 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -111,6 +111,13 @@
 }
 
 #define arch_phys_wc_add arch_phys_wc_add
+#ifndef arch_phys_wc_index
+static inline int arch_phys_wc_index(int handle)
+{
+	return -1;
+}
+#define arch_phys_wc_index arch_phys_wc_index
+#endif
 #endif
 
 #endif /* _LINUX_IO_H */