diff --git a/neuron_reg_access.h b/neuron_reg_access.h
index a547c4b..c0f4db8 100644
--- a/neuron_reg_access.h
+++ b/neuron_reg_access.h
@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include <linux/io.h>
 #include <asm/bug.h>
 #include <asm/barrier.h>
 #include <asm/delay.h>