diff --git a/artiq/coredevice/analyzer.py b/artiq/coredevice/analyzer.py
index b3b187d69..bcc445871 100644
--- a/artiq/coredevice/analyzer.py
+++ b/artiq/coredevice/analyzer.py
@@ -58,8 +58,9 @@ def decode_message(data):
 
 
 def decode_dump(data):
-    parts = struct.unpack(">IQI", data[:16])
-    sent_bytes, total_byte_count, overflow_occured = parts
+    parts = struct.unpack(">IQbbbb", data[:16])
+    (sent_bytes, total_byte_count,
+     overflow_occured, log_channel, dds_channel, _) = parts
 
     if sent_bytes + 16 != len(data):
         raise ValueError("analyzer dump has incorrect length")
diff --git a/artiq/runtime/analyzer.c b/artiq/runtime/analyzer.c
index b2a517888..9a3440edb 100644
--- a/artiq/runtime/analyzer.c
+++ b/artiq/runtime/analyzer.c
@@ -10,7 +10,10 @@
 struct analyzer_header {
     unsigned int sent_bytes;
     unsigned long long int total_byte_count;
-    unsigned int overflow_occured;
+    unsigned char overflow_occured;
+    unsigned char log_channel;
+    unsigned char dds_channel;
+    unsigned char padding;
 } __attribute__((packed));
 
 
@@ -68,6 +71,9 @@ void analyzer_start(void)
         analyzer_header.sent_bytes = analyzer_header.total_byte_count;
 
     analyzer_header.overflow_occured = rtio_analyzer_message_encoder_overflow_read();
+    analyzer_header.log_channel = 0;
+    analyzer_header.dds_channel = CONFIG_RTIO_DDS_CHANNEL;
+    analyzer_header.padding = 0;
 
     offset_consumed = 0;
     offset_sent = 0;