diff --git a/protocol/ps2_interrupt.c b/protocol/ps2_interrupt.c
index 259d254..8114442 100644
--- a/protocol/ps2_interrupt.c
+++ b/protocol/ps2_interrupt.c
@@ -43,6 +43,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <avr/interrupt.h>
 #include <util/delay.h>
 #include "ps2.h"
+#include "ps2_io.h"
 #include "print.h"
 
 
diff --git a/protocol/ps2_usart.c b/protocol/ps2_usart.c
index c2d9d0a..6936ca7 100644
--- a/protocol/ps2_usart.c
+++ b/protocol/ps2_usart.c
@@ -43,6 +43,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <avr/interrupt.h>
 #include <util/delay.h>
 #include "ps2.h"
+#include "ps2_io.h"
 #include "print.h"