diff --git a/module_usb_audio/audio.xc b/module_usb_audio/audio.xc
index 174d04d9..116f83bd 100755
--- a/module_usb_audio/audio.xc
+++ b/module_usb_audio/audio.xc
@@ -368,7 +368,7 @@ unsigned static deliver(chanend c_out, chanend ?c_spd_out, unsigned divide, unsi
 #pragma loop unroll
     for(int i = 0; i < I2S_WIRES_ADC; i++)
     {
-        asm("setpt res[%0], %1"::"r"(p_i2s_adc[i]),"r"(tmp-1));
+        asm("setpt res[%0], %1"::"r"(p_i2s_adc[i]),"r"(tmp+31));
     }
 #endif