diff --git a/include/drivers/arm/tzc400.h b/include/drivers/arm/tzc400.h
index aacd5df..5f8a48f 100644
--- a/include/drivers/arm/tzc400.h
+++ b/include/drivers/arm/tzc400.h
@@ -90,6 +90,8 @@
 #define TZC_400_REGION_SIZE			U(0x20)
 #define TZC_400_ACTION_OFF			U(0x4)
 
+#define FILTER_OFFSET				U(0x10)
+
 #ifndef __ASSEMBLER__
 
 #include <cdefs.h>
@@ -110,6 +112,7 @@
 void tzc400_set_action(unsigned int action);
 void tzc400_enable_filters(void);
 void tzc400_disable_filters(void);
+int tzc400_it_handler(void);
 
 static inline void tzc_init(uintptr_t base)
 {