diff --git a/Makefile b/Makefile
index 4f692b3..5f3fdbc 100644
--- a/Makefile
+++ b/Makefile
@@ -74,7 +74,7 @@ DEFS += -DSTM32F1 -D$(BOARD)
 
 # C flags
 CFLAGS += -Os -g
-CFLAGS += -std=c99 -Wpedantic -Wall -Werror -Wundef -Wextra -Wshadow -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes
+CFLAGS += -std=c99 -Wpedantic -Wall -Werror -Wundef -Wextra -Wshadow -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes -Wstrict-overflow=5
 CFLAGS += -fno-common -ffunction-sections -fdata-sections
 CFLAGS += -I. -I$(INCLUDE_DIR) $(patsubst %,-I%,$(LIB))
 CFLAGS += $(DEFS)