diff --git a/plat/mediatek/mt8173/drivers/spm/spm_mcdi.h b/plat/mediatek/mt8173/drivers/spm/spm_mcdi.h
index 4e9aa3e..4d1f990 100644
--- a/plat/mediatek/mt8173/drivers/spm/spm_mcdi.h
+++ b/plat/mediatek/mt8173/drivers/spm/spm_mcdi.h
@@ -31,6 +31,7 @@
 #define __SPM_MCDI_H__
 
 void spm_mcdi_wakeup_all_cores(void);
+void spm_mcdi_prepare_for_mtcmos(void);
 void spm_mcdi_prepare_for_off_state(unsigned long mpidr, unsigned int afflvl);
 void spm_mcdi_finish_for_on_state(unsigned long mpidr, unsigned int afflvl);