diff --git a/src/modules/gpio_led/module.mk b/src/modules/gpio_led/module.mk
index 3b8553489d..70c75b10cb 100644
--- a/src/modules/gpio_led/module.mk
+++ b/src/modules/gpio_led/module.mk
@@ -37,3 +37,5 @@
 
 MODULE_COMMAND	= gpio_led
 SRCS			= gpio_led.c
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/modules/unit_test/module.mk b/src/modules/unit_test/module.mk
index f00b0f5926..5000790a59 100644
--- a/src/modules/unit_test/module.mk
+++ b/src/modules/unit_test/module.mk
@@ -37,3 +37,4 @@
 
 SRCS		 = unit_test.cpp
 
+MAXOPTIMIZATION	 = -Os
diff --git a/src/systemcmds/esc_calib/module.mk b/src/systemcmds/esc_calib/module.mk
index 990c567681..ce87eb3e2c 100644
--- a/src/systemcmds/esc_calib/module.mk
+++ b/src/systemcmds/esc_calib/module.mk
@@ -39,3 +39,5 @@ MODULE_COMMAND	 = esc_calib
 SRCS		 = esc_calib.c
 
 MODULE_STACKSIZE = 4096
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/systemcmds/mtd/module.mk b/src/systemcmds/mtd/module.mk
index b3fceceb5c..1bc4f414ec 100644
--- a/src/systemcmds/mtd/module.mk
+++ b/src/systemcmds/mtd/module.mk
@@ -4,3 +4,5 @@
 
 MODULE_COMMAND	 = mtd
 SRCS		 = mtd.c 24xxxx_mtd.c
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/systemcmds/nshterm/module.mk b/src/systemcmds/nshterm/module.mk
index e2fa0ff804..7d2c59f913 100644
--- a/src/systemcmds/nshterm/module.mk
+++ b/src/systemcmds/nshterm/module.mk
@@ -39,3 +39,5 @@ MODULE_COMMAND	 = nshterm
 SRCS		 = nshterm.c
 
 MODULE_STACKSIZE = 1400
+
+MAXOPTIMIZATION	 = -Os
diff --git a/src/systemcmds/pwm/module.mk b/src/systemcmds/pwm/module.mk
index 13a24150f2..a51ac8e0cf 100644
--- a/src/systemcmds/pwm/module.mk
+++ b/src/systemcmds/pwm/module.mk
@@ -39,3 +39,5 @@ MODULE_COMMAND	 = pwm
 SRCS		 = pwm.c
 
 MODULE_STACKSIZE = 1800
+
+MAXOPTIMIZATION	 = -Os