diff --git a/module_usb_aud_shared/usb_buffer/decouple.xc b/module_usb_aud_shared/usb_buffer/decouple.xc
index ee7e5932..c72e7cf7 100644
--- a/module_usb_aud_shared/usb_buffer/decouple.xc
+++ b/module_usb_aud_shared/usb_buffer/decouple.xc
@@ -1257,8 +1257,8 @@ void decouple(chanend c_mix_out,
                         /* There is room in the collecting buffer for the data */
                         xc_ptr p = (iap_to_host_buffer_being_collected + 4) + iap_data_collected_from_device;                                                            
                         // Add data to the buffer
-                        write_via_xc_ptr(p, datum_iap);
-                        iap_data_collected_from_device += 4;
+                        write_byte_via_xc_ptr_indexed(p, 0, datum_iap);
+                        iap_data_collected_from_device += 1;
                     }
                     else 
                     {
diff --git a/module_usb_aud_shared/usb_buffer/xc_ptr.h b/module_usb_aud_shared/usb_buffer/xc_ptr.h
index e2750668..8dfff2fd 100644
--- a/module_usb_aud_shared/usb_buffer/xc_ptr.h
+++ b/module_usb_aud_shared/usb_buffer/xc_ptr.h
@@ -12,6 +12,7 @@ inline xc_ptr array_to_xc_ptr(unsigned a[]) {
 #define write_via_xc_ptr(p,x)   asm("stw %0, %1[0]"::"r"(x),"r"(p))
 
 #define write_via_xc_ptr_indexed(p,i,x)   asm("stw %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
+#define write_byte_via_xc_ptr_indexed(p,i,x)   asm("st8 %0, %1[%2]"::"r"(x),"r"(p),"r"(i))
 
 #define read_via_xc_ptr(x,p)  asm("ldw %0, %1[0]":"=r"(x):"r"(p));