diff --git a/examples/rtt/rtt.js b/examples/rtt/rtt.js
index 4aaeccf..7950865 100644
--- a/examples/rtt/rtt.js
+++ b/examples/rtt/rtt.js
@@ -112,6 +112,7 @@ class RTT {
     async read (bufId) {
         var buf = this.bufUp[bufId];
 
+        buf.RdOff = await this.processor.readMem32(buf.bufAddr + 16);
         buf.WrOff = await this.processor.readMem32(buf.bufAddr + 12);
 
         if (buf.WrOff > buf.RdOff) {
@@ -136,6 +137,7 @@ class RTT {
         var buf = this.bufDown[bufId];
 
         buf.RdOff = await this.processor.readMem32(buf.bufAddr + 16);
+        buf.WrOff = await this.processor.readMem32(buf.bufAddr + 12);
 
         if (buf.WrOff >= buf.RdOff)
             var num_avail = buf.SizeOfBuffer - (buf.WrOff - buf.RdOff);