osMessageGet causes HardFault when IRQ disabled

Hello All, the following code is generating a HardFault. I'm sure I've missed something stupid:

void Thread_Debug2(void const *argument)
{
        // locals
        Debug_Struct * pDbgStrct = 0;
        osStatus Status = osOK;
        uint32_t Placements2 = 0;

        // Start
        while(1)
        {
                // disable irq
                __disable_irq();

                // get message, here the hardfault occurs
                pDbgStrct = (Debug_Struct *)osMessageGet(MsgQueue_Debug1, 0).value.v;

                // enable irq
                __enable_irq();

                // free memory
                Status = osPoolFree(MemPool_Debug1, pDbgStrct);

                // check status
                if(Status == osOK)
                {
                        Placements2++;
                }
        }
}

In my opinion, the osMessageGet should be able to get a message from a message queue even when no interrupt is activated...