diff --git a/arch/arm/src/calypso/calypso_spi.c b/arch/arm/src/calypso/calypso_spi.c
index fda4415c23c..881d66da2bc 100644
--- a/arch/arm/src/calypso/calypso_spi.c
+++ b/arch/arm/src/calypso/calypso_spi.c
@@ -41,6 +41,7 @@
 #include <nuttx/spi/spi.h>
 
 #include <unistd.h>
+#include <semaphore.h>
 #include <debug.h>
 
 #include "up_arch.h"