diff --git a/pd/src/s_audio_alsa.c b/pd/src/s_audio_alsa.c
index 2cca80e4f0558f48521fbe1d28af31608c218b24..9cbe017d69b3f1efc89e5c5e3019a72892fc126b 100644
--- a/pd/src/s_audio_alsa.c
+++ b/pd/src/s_audio_alsa.c
@@ -421,7 +421,8 @@ int alsa_send_dacs(void)
     callno++;
 #endif
 
-    alsa_checkiosync();     /* check I/O are in sync and data not late */
+    if (alsa_nindev > 0 && alsa_noutdev > 0)
+        alsa_checkiosync();     /* check I/O are in sync and data not late */
 
     for (iodev = 0; iodev < alsa_nindev; iodev++)
     {