diff --git a/src/hardware/beaglelogic/api.c b/src/hardware/beaglelogic/api.c
index 12af5c1d..604849c4 100644
--- a/src/hardware/beaglelogic/api.c
+++ b/src/hardware/beaglelogic/api.c
@@ -165,6 +165,7 @@ static int dev_open(struct sr_dev_inst *sdi)
 	/* Set fd and local attributes */
 	devc->pollfd.fd = devc->fd;
 	devc->pollfd.events = G_IO_IN;
+	devc->pollfd.revents = 0;
 
 	/* Get the default attributes */
 	beaglelogic_get_samplerate(devc);
diff --git a/src/session.c b/src/session.c
index 20c9ce5f..499025b5 100644
--- a/src/session.c
+++ b/src/session.c
@@ -389,7 +389,6 @@ static int sr_session_iteration(struct sr_session *session, gboolean block)
 
 #ifdef HAVE_LIBUSB_1_0
 	if (session->ctx->usb_source_present) {
-		timeout = block ? 0 : session->source_timeout;
 		ret = libusb_get_next_timeout(session->ctx->libusb_ctx, &tv);
 		if (ret < 0) {
 			sr_err("Error getting libusb timeout: %s",
@@ -856,6 +855,7 @@ SR_API int sr_session_source_add(struct sr_session *session, int fd,
 
 	p.fd = fd;
 	p.events = events;
+	p.revents = 0;
 
 	return _sr_session_source_add(session, &p, timeout, cb, cb_data, (gintptr)fd);
 }
@@ -908,6 +908,7 @@ SR_API int sr_session_source_add_channel(struct sr_session *session,
 #else
 	p.fd = g_io_channel_unix_get_fd(channel);
 	p.events = events;
+	p.revents = 0;
 #endif
 
 	return _sr_session_source_add(session, &p, timeout, cb, cb_data, (gintptr)channel);
diff --git a/src/usb.c b/src/usb.c
index f5b20c99..5038441c 100644
--- a/src/usb.c
+++ b/src/usb.c
@@ -251,6 +251,7 @@ SR_PRIV int usb_source_add(struct sr_session *session, struct sr_context *ctx,
 	/* Add event, set by USB wait thread, to session poll set. */
 	ctx->usb_pollfd.fd = ctx->usb_wait_complete_event;
 	ctx->usb_pollfd.events = G_IO_IN;
+	ctx->usb_pollfd.revents = 0;
 	ctx->usb_cb = cb;
 	ctx->usb_cb_data = cb_data;
 	sr_session_source_add_pollfd(session, &ctx->usb_pollfd, timeout,