Index: fact/FADctrl/FAD.cc
===================================================================
--- fact/FADctrl/FAD.cc	(revision 11232)
+++ fact/FADctrl/FAD.cc	(revision 11259)
@@ -1067,5 +1067,5 @@
 
 	// Write event header, trigger cells and ADC data to file
-	if (write(Datafile, EHeader, sizeof(EventHeader)+NChips*sizeof(int)+ActiveBoards.size()*NChips*NChannels*NBins*sizeof(short)) == -1) Error = errno;
+	if (write(Datafile, EHeader, sizeof(EventHeader)+FileRHeader.NBoards*NChips*(sizeof(int)+NChannels*NBins*sizeof(short))) == -1) Error = errno;
 
 	NumEvents++;