diff --git a/src/iso.c b/src/iso.c
index 007d72c..36d5d25 100644
--- a/src/iso.c
+++ b/src/iso.c
@@ -160,7 +160,7 @@ static int do_iso_init(raw1394handle_t handle,
  * raw1394_iso_xmit_init - initialize isochronous transmission
  * @handler: handler function for queueing packets
  * @buf_packets: number of isochronous packets to buffer
- * @max_packet_size: largest packet you need to handle, in bytes (not including the 8-byte isochronous header)
+ * @max_packet_size: largest packet you need to handle, in bytes (not including the isochronous header)
  * @channel: isochronous channel on which to transmit
  * @speed: speed at which to transmit
  * @irq_interval: maximum latency of wake-ups, in packets (-1 if you don't care)
@@ -186,7 +186,7 @@ int raw1394_iso_xmit_init(raw1394handle_t handle,
  * raw1394_iso_recv_init - initialize isochronous reception
  * @handler: handler function for receiving packets
  * @buf_packets: number of isochronous packets to buffer
- * @max_packet_size: largest packet you need to handle, in bytes (not including the 8-byte isochronous header)
+ * @max_packet_size: largest packet you need to handle, in bytes (not including the isochronous header)
  * @channel: isochronous channel to receive
  * @speed: speed at which to receive
  * @irq_interval: maximum latency of wake-ups, in packets (-1 if you don't care)
@@ -275,6 +275,9 @@ static int _raw1394_iso_xmit_queue_packets(raw1394handle_t handle)
 		packets_done++;
 
 		if(disp == RAW1394_ISO_DEFER) {
+			/* queue an event so that we don't hang in the next read() */
+			if(ioctl(handle->fd, RAW1394_ISO_QUEUE_ACTIVITY, 0))
+				return -1;
 			break;
 		} else if(disp == RAW1394_ISO_ERROR) {
 			retval = -1;
@@ -377,6 +380,9 @@ static int _raw1394_iso_recv_packets(raw1394handle_t handle)
 		packets_done++;
 		
 		if(disp == RAW1394_ISO_DEFER) {
+			/* queue an event so that we don't hang in the next read() */
+			if(ioctl(handle->fd, RAW1394_ISO_QUEUE_ACTIVITY, 0))
+				return -1;
 			break;
 		} else if(disp == RAW1394_ISO_ERROR) {
 			retval = -1;
diff --git a/src/kernel-raw1394.h b/src/kernel-raw1394.h
index c6e5c59..24d00c9 100644
--- a/src/kernel-raw1394.h
+++ b/src/kernel-raw1394.h
@@ -130,6 +130,7 @@ typedef struct arm_request_response {
 #define RAW1394_ISO_GET_STATUS       5  /* arg: raw1394_iso_status* */
 #define RAW1394_ISO_PRODUCE_CONSUME  6  /* arg: int, # of packets */
 #define RAW1394_ISO_SHUTDOWN         7
+#define RAW1394_ISO_QUEUE_ACTIVITY   9
 
 /* per-packet metadata embedded in the ringbuffer */
 /* must be identical to hpsb_iso_packet_info in iso.h! */
diff --git a/src/raw1394.h b/src/raw1394.h
index 42dfe21..8364301 100644
--- a/src/raw1394.h
+++ b/src/raw1394.h
@@ -72,23 +72,23 @@ enum raw1394_iso_disposition {
 extern "C" {
 #endif
 
-typedef int (*raw1394_iso_xmit_handler_t)(raw1394handle_t,
-					  unsigned char *data,
-					  unsigned int *len,
-					  unsigned char *tag,
-					  unsigned char *sy,
-					  unsigned int cycle,
-					  unsigned int dropped);
-	
-typedef int (*raw1394_iso_recv_handler_t)(raw1394handle_t,
-					  unsigned char *data,
-					  unsigned int len,
-					  unsigned char channel,
-					  unsigned char tag,
-					  unsigned char sy,
-					  unsigned int cycle,
-					  unsigned int dropped);
+typedef enum raw1394_iso_disposition (*raw1394_iso_xmit_handler_t)(raw1394handle_t,
+								   unsigned char *data,
+								   unsigned int *len,
+								   unsigned char *tag,
+								   unsigned char *sy,
+								   unsigned int cycle,
+								   unsigned int dropped);
 	
+typedef enum raw1394_iso_disposition (*raw1394_iso_recv_handler_t)(raw1394handle_t,
+								   unsigned char *data,
+								   unsigned int len,
+								   unsigned char channel,
+								   unsigned char tag,
+								   unsigned char sy,
+								   unsigned int cycle,
+								   unsigned int dropped);
+
 int raw1394_iso_xmit_init(raw1394handle_t handle,
 			  raw1394_iso_xmit_handler_t handler,
 			  unsigned int buf_packets,