diff --git a/rtos/MemoryPool.h b/rtos/MemoryPool.h
index 02c34bdcd4..431b5d6894 100644
--- a/rtos/MemoryPool.h
+++ b/rtos/MemoryPool.h
@@ -183,8 +183,7 @@ public:
 
 private:
     osMemoryPoolId_t             _id;
-    /* osMemoryPoolNew requires that pool block size is a multiple of 4 bytes. */
-    char                         _pool_mem[((sizeof(T) + 3) & ~3) * pool_sz];
+    char                         _pool_mem[MBED_RTOS_STORAGE_MEM_POOL_MEM_SIZE(pool_sz, sizeof(T))];
     mbed_rtos_storage_mem_pool_t _obj_mem;
 };
 /** @}*/
@@ -192,5 +191,3 @@ private:
 
 }
 #endif
-
-
diff --git a/rtos/TARGET_CORTEX/mbed_rtos_storage.h b/rtos/TARGET_CORTEX/mbed_rtos_storage.h
index 66c1d07808..2a0338baed 100644
--- a/rtos/TARGET_CORTEX/mbed_rtos_storage.h
+++ b/rtos/TARGET_CORTEX/mbed_rtos_storage.h
@@ -52,6 +52,9 @@ typedef osRtxEventFlags_t mbed_rtos_storage_event_flags_t;
 typedef osRtxMessage_t mbed_rtos_storage_message_t;
 typedef osRtxTimer_t mbed_rtos_storage_timer_t;
 
+#define MBED_RTOS_STORAGE_MEM_POOL_MEM_SIZE(block_count, block_size) \
+  osRtxMemoryPoolMemSize(block_count, block_size)
+
 #ifdef __cplusplus
 }
 #endif