diff --git a/rdpsnd.c b/rdpsnd.c
index 41e1b2d..a26bace 100644
--- a/rdpsnd.c
+++ b/rdpsnd.c
@@ -104,6 +104,18 @@ rdpsnd_process_negotiate(STREAM in)
 			in_uint16_le(in, format->wBitsPerSample);
 			in_uint16_le(in, format->cbSize);
 
+			/* read in the buffer of unknown use */
+			int readcnt = format->cbSize;
+			int discardcnt = 0;
+			if (format->cbSize > MAX_CBSIZE)
+			{
+				fprintf(stderr, "cbSize too large for buffer: %d\n", format->cbSize);
+				readcnt = MAX_CBSIZE;
+				discardcnt = format->cbSize - MAX_CBSIZE;
+			}
+			in_uint8a(in, format->cb, readcnt);
+			in_uint8s(in, discardcnt);
+
 			if (device_available && wave_out_format_supported(format))
 			{
 				format_count++;
diff --git a/types.h b/types.h
index 60c5098..04e8120 100644
--- a/types.h
+++ b/types.h
@@ -119,6 +119,8 @@ typedef struct _VCHANNEL
 }
 VCHANNEL;
 
+#define MAX_CBSIZE 256
+
 /* RDPSND */
 typedef struct {
     uint16 wFormatTag;
@@ -128,6 +130,7 @@ typedef struct {
     uint16 nBlockAlign;
     uint16 wBitsPerSample;
     uint16 cbSize;
+    uint8  cb[MAX_CBSIZE];
 } WAVEFORMATEX;
 
 /* RDPDR */