diff --git a/CEP/DP3/AOFlagger/src/msio/timestepaccessor.cpp b/CEP/DP3/AOFlagger/src/msio/timestepaccessor.cpp
index 785f3e90c4d4f806f5f2547ac820cb8e26a38c26..52cf125720570cbc9816faedbbebc7312f267e5b 100644
--- a/CEP/DP3/AOFlagger/src/msio/timestepaccessor.cpp
+++ b/CEP/DP3/AOFlagger/src/msio/timestepaccessor.cpp
@@ -237,7 +237,7 @@ void TimestepAccessor::emptyWriteBuffer()
 	{
 		SetInfo &set = *i;
 
-		openSet(set);
+		openSet(set, true);
 
 		for(unsigned writeBufferIndex = 0; writeBufferIndex < _inWriteBuffer; ++writeBufferIndex)
 		{