diff --git a/arch/c5471/src/up_initialize.c b/arch/c5471/src/up_initialize.c
index 8b85ecd719b..bae36548bbe 100644
--- a/arch/c5471/src/up_initialize.c
+++ b/arch/c5471/src/up_initialize.c
@@ -41,6 +41,7 @@
 #include <sys/types.h>
 #include <debug.h>
 #include <nuttx/arch.h>
+#include <nuttx/fs.h>
 #include "up_internal.h"
 
 /************************************************************
diff --git a/arch/c5471/src/up_internal.h b/arch/c5471/src/up_internal.h
index 88ed459f3ce..b1256130e36 100644
--- a/arch/c5471/src/up_internal.h
+++ b/arch/c5471/src/up_internal.h
@@ -110,6 +110,10 @@ extern void up_serialinit(void);
 
 extern void up_timerinit(void);
 
+/* Defined in up_irq.c */
+
+extern void up_maskack_irq(int irq);
+
 #endif /* __ASSEMBLY__ */
 
 #endif  /* __UP_INTERNAL_H */