diff --git a/src/drivers/stm32/adc/module.mk b/src/drivers/stm32/adc/module.mk
index 48620feea8..38ea490a0e 100644
--- a/src/drivers/stm32/adc/module.mk
+++ b/src/drivers/stm32/adc/module.mk
@@ -40,3 +40,5 @@ MODULE_COMMAND	= adc
 SRCS		= adc.cpp
 
 INCLUDE_DIRS	+= $(NUTTX_SRC)/arch/arm/src/stm32 $(NUTTX_SRC)/arch/arm/src/common
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/drivers/stm32/module.mk b/src/drivers/stm32/module.mk
index bb751c7f68..54428e270d 100644
--- a/src/drivers/stm32/module.mk
+++ b/src/drivers/stm32/module.mk
@@ -41,3 +41,5 @@ SRCS		= drv_hrt.c \
 		  drv_pwm_servo.c
 
 INCLUDE_DIRS	+= $(NUTTX_SRC)/arch/arm/src/stm32 $(NUTTX_SRC)/arch/arm/src/common
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/drivers/stm32/tone_alarm/module.mk b/src/drivers/stm32/tone_alarm/module.mk
index 827cf30b27..25a194ef61 100644
--- a/src/drivers/stm32/tone_alarm/module.mk
+++ b/src/drivers/stm32/tone_alarm/module.mk
@@ -40,3 +40,5 @@ MODULE_COMMAND	= tone_alarm
 SRCS		= tone_alarm.cpp
 
 INCLUDE_DIRS	+= $(NUTTX_SRC)/arch/arm/src/stm32 $(NUTTX_SRC)/arch/arm/src/common
+
+MAXOPTIMIZATION	 = -Os