diff --git a/libraries/rtos/rtx/TARGET_CORTEX_M/RTX_Conf_CM.c b/libraries/rtos/rtx/TARGET_CORTEX_M/RTX_Conf_CM.c
index d3f0452c2a..11c8a05e3f 100755
--- a/libraries/rtos/rtx/TARGET_CORTEX_M/RTX_Conf_CM.c
+++ b/libraries/rtos/rtx/TARGET_CORTEX_M/RTX_Conf_CM.c
@@ -70,9 +70,9 @@
 #      define OS_SCHEDULERSTKSIZE    256
 #  elif defined(TARGET_LPC11U24) || defined(TARGET_LPC11U35_401)  || defined(TARGET_LPC11U35_501) || defined(TARGET_LPCCAPPUCCINO)  || defined(TARGET_LPC1114) \
    || defined(TARGET_LPC812)   || defined(TARGET_KL25Z)         || defined(TARGET_KL05Z)        || defined(TARGET_STM32F100RB)  || defined(TARGET_STM32F051R8) \
-   || defined(TARGET_STM32F103RB) || defined(TARGET_LPC824) || defined(TARGET_STM32F302R8) || defined(TARGET_STM32L053R8) || defined(TARGET_STM32L053C8)
+   || defined(TARGET_STM32F103RB) || defined(TARGET_LPC824) || defined(TARGET_STM32F302R8)
 #      define OS_SCHEDULERSTKSIZE    128
-#  elif defined(TARGET_STM32F334R8) || defined(TARGET_STM32F334C8)
+#  elif defined(TARGET_STM32F334R8) || defined(TARGET_STM32F334C8) || defined(TARGET_STM32L053R8) || defined(TARGET_STM32L053C8)
 #      define OS_SCHEDULERSTKSIZE    112
 #  else
 #    error "no target defined"
diff --git a/libraries/rtos/rtx/TARGET_CORTEX_M/cmsis_os.h b/libraries/rtos/rtx/TARGET_CORTEX_M/cmsis_os.h
index 9f90ace987..d8fcf8edd0 100644
--- a/libraries/rtos/rtx/TARGET_CORTEX_M/cmsis_os.h
+++ b/libraries/rtos/rtx/TARGET_CORTEX_M/cmsis_os.h
@@ -121,7 +121,11 @@ used throughout the whole project.
 #    define WORDS_STACK_SIZE   128
 #endif
 
-#define DEFAULT_STACK_SIZE         (WORDS_STACK_SIZE*4)
+#if defined(TARGET_STM32L053R8) || defined(TARGET_STM32L053C8)
+#    define DEFAULT_STACK_SIZE         (WORDS_STACK_SIZE*1)
+#else
+#    define DEFAULT_STACK_SIZE         (WORDS_STACK_SIZE*4)
+#endif
 
 
 /// \note MUST REMAIN UNCHANGED: \b osFeature_xxx shall be consistent in every CMSIS-RTOS.