Bug in QAudioOutput: Invalid use of "waveOutUnprepareHeader"

void QAudioOutputPrivate::freeBlocks(WAVEHDR* blockArray)
	{
	    WAVEHDR* blocks = blockArray;
	
	    int count = buffer_size/period_size;
	
	    for(int i = 0; i < count; i++) {
	        waveOutUnprepareHeader(hWaveOut,&blocks[i], sizeof(WAVEHDR));
	        blocks+=sizeof(WAVEHDR);
	    }
                  HeapFree(GetProcessHeap(), 0, blockArray);
	}

 
...
	    for(int i = 0; i < count; i++) {
	        waveOutUnprepareHeader(hWaveOut,blocks, sizeof(WAVEHDR));
	        blocks+=sizeof(WAVEHDR);
	    }
...

...
	    for(int i = 0; i < count; i++) {
	        if(blocks->dwFlags & WHDR_PREPARED)
	               waveOutUnprepareHeader(hWaveOut,blocks, sizeof(WAVEHDR));
	        blocks+=sizeof(WAVEHDR);
	    }
...