diff --git a/plat/st/stm32mp1/platform.mk b/plat/st/stm32mp1/platform.mk
index 8d4320a..ea8ed91 100644
--- a/plat/st/stm32mp1/platform.mk
+++ b/plat/st/stm32mp1/platform.mk
@@ -38,6 +38,7 @@
 endif
 
 TF_CFLAGS		+=	-Wsign-compare
+TF_CFLAGS		+=	-Wformat-signedness
 
 # Not needed for Cortex-A7
 WORKAROUND_CVE_2017_5715:=	0