diff --git a/rtos/rtx/TARGET_CORTEX_A/RTX_CM_lib.h b/rtos/rtx/TARGET_CORTEX_A/RTX_CM_lib.h
index 752e822609..4823c77258 100644
--- a/rtos/rtx/TARGET_CORTEX_A/RTX_CM_lib.h
+++ b/rtos/rtx/TARGET_CORTEX_A/RTX_CM_lib.h
@@ -51,7 +51,7 @@
 #define _declare_box(pool,size,cnt)  uint32_t pool[(((size)+3)/4)*(cnt) + 3]
 #define _declare_box8(pool,size,cnt) uint64_t pool[(((size)+7)/8)*(cnt) + 2]
 
-#define OS_TCB_SIZE     60
+#define OS_TCB_SIZE     64
 #define OS_TMR_SIZE     8
 
 #if defined (__CC_ARM) && !defined (__MICROLIB)
diff --git a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
index 7d2d246c27..74db091961 100644
--- a/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
+++ b/rtos/rtx/TARGET_CORTEX_M/RTX_CM_lib.h
@@ -52,7 +52,7 @@
 #define _declare_box(pool,size,cnt)  uint32_t pool[(((size)+3)/4)*(cnt) + 3]
 #define _declare_box8(pool,size,cnt) uint64_t pool[(((size)+7)/8)*(cnt) + 2]
 
-#define OS_TCB_SIZE     60
+#define OS_TCB_SIZE     64
 #define OS_TMR_SIZE     8
 
 typedef void    *OS_ID;