diff --git a/hal/targets.json b/hal/targets.json
index 48525f53e5f..1d48695e559 100644
--- a/hal/targets.json
+++ b/hal/targets.json
@@ -715,6 +715,7 @@
         "progen": {"target": "nucleo-f302r8"},
         "detect_code": ["0705"],
         "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
+        "default_build": "small",        
         "release_versions": ["2"]
     },
     "NUCLEO_F303K8": {
@@ -726,6 +727,7 @@
         "inherits": ["Target"],
         "progen": {"target": "nucleo-f303k8"},
         "detect_code": ["0775"],
+        "default_build": "small",
         "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
         "release_versions": ["2"]
     },
@@ -751,6 +753,7 @@
         "progen": {"target": "nucleo-f334r8"},
         "detect_code": ["0735"],
         "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
+        "default_build": "small",
         "release_versions": ["2"]
     },
     "NUCLEO_F401RE": {
@@ -1025,7 +1028,8 @@
         "progen": {"target": "disco-f334c8"},
         "detect_code": ["0810"],
         "device_has": ["ANALOGIN", "ANALOGOUT", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "RTC_LSI", "SERIAL", "SERIAL_ASYNCH", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
-        "release_versions": ["2"]
+        "default_build": "small",        
+	"release_versions": ["2"]
     },
     "DISCO_F407VG": {
         "inherits": ["Target"],
diff --git a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
index b9aa85744e3..4c67a307eaa 100644
--- a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
+++ b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
@@ -351,7 +351,8 @@ __attribute__((used)) void _mutex_release (OS_ID *mutex) {
 /* Main Thread definition */
 extern void pre_main (void);
 
-#if defined(TARGET_MCU_NRF51822) || defined(TARGET_MCU_NRF52832)
+#if defined(TARGET_MCU_NRF51822) || defined(TARGET_MCU_NRF52832) || defined (TARGET_STM32F334R8) ||\
+    defined(TARGET_STM32F302R8) || defined(TARGET_STM32F303K8) || defined (TARGET_STM32F334C8)
 static uint32_t thread_stack_main[DEFAULT_STACK_SIZE / sizeof(uint32_t)];
 #else
 static uint32_t thread_stack_main[DEFAULT_STACK_SIZE * 2 / sizeof(uint32_t)];