diff --git a/src/base/circlebuf.cc b/src/base/circlebuf.cc
index 06d0075b2d..2f04bc16e0 100644
--- a/src/base/circlebuf.cc
+++ b/src/base/circlebuf.cc
@@ -67,6 +67,7 @@ CircleBuf::flush()
 {
     _start = 0;
     _stop = 0;
+    _size = 0;
     _rollover = false;
 }