diff --git a/arduino-mk/Arduino.mk b/arduino-mk/Arduino.mk
index 8fc8e5c..c85a38f 100644
--- a/arduino-mk/Arduino.mk
+++ b/arduino-mk/Arduino.mk
@@ -650,7 +650,7 @@ USER_LIB_OBJS = $(patsubst $(USER_LIB_PATH)/%.cpp,$(OBJDIR)/libs/%.o,$(USER_LIB_
 # Using += instead of =, so that CPPFLAGS can be set per sketch level
 CPPFLAGS      += -mmcu=$(MCU) -DF_CPU=$(F_CPU) -DARDUINO=$(ARDUINO_VERSION) \
 			-I. -I$(ARDUINO_CORE_PATH) -I$(ARDUINO_VAR_PATH)/$(VARIANT) \
-			$(SYS_INCLUDES) $(USER_INCLUDES) -g -Os -w -Wall \
+			$(SYS_INCLUDES) $(USER_INCLUDES) -g -Os -Wall \
 			-ffunction-sections -fdata-sections
 CFLAGS        += -std=gnu99
 CXXFLAGS      += -fno-exceptions