Index: uspace/drv/audio/sb16/dsp.c
===================================================================
--- uspace/drv/audio/sb16/dsp.c	(revision 5b8e08e0e2732bd885d56883326360c90f6d08b1)
+++ uspace/drv/audio/sb16/dsp.c	(revision 3efaeb6a53cd365691844fa512b3ab759b740609)
@@ -411,7 +411,8 @@
 
 	/* Client requested regular events */
-	if (frames) {
-		if (!dsp->event_session)
-			return EINVAL;
+	if (frames && !dsp->event_session)
+		return EINVAL;
+
+	if (dsp->event_session) {
 		dsp->event_exchange = async_exchange_begin(dsp->event_session);
 		if (!dsp->event_exchange)
@@ -483,7 +484,8 @@
 
 	/* Client requested regular events */
-	if (frames) {
-		if (!dsp->event_session)
-			return EINVAL;
+	if (frames && !dsp->event_session)
+		return EINVAL;
+
+	if (dsp->event_session) {
 		dsp->event_exchange = async_exchange_begin(dsp->event_session);
 		if (!dsp->event_exchange)