diff --git a/module_usb_audio/main.xc b/module_usb_audio/main.xc
index 646406e5..9991f2d8 100755
--- a/module_usb_audio/main.xc
+++ b/module_usb_audio/main.xc
@@ -151,7 +151,9 @@ on tile[AUDIO_IO_TILE] :  buffered in port:1 p_midi_rx      = PORT_MIDI_IN;
 on tile[AUDIO_IO_TILE] : clock    clk_midi                  = CLKBLK_MIDI;
 #endif
 
+#if defined(SPDIF) || defined(ADAT_TX)
 on tile[AUDIO_IO_TILE] : clock    clk_mst_spd               = CLKBLK_SPDIF_TX;
+#endif
 
 #ifdef SPDIF_RX
 on tile[XUD_TILE] : clock    clk_spd_rx                     = CLKBLK_SPDIF_RX;