diff --git a/include/dos_inc.h b/include/dos_inc.h
index 98e76547..070bb3b2 100644
--- a/include/dos_inc.h
+++ b/include/dos_inc.h
@@ -509,6 +509,7 @@ public:
 	void SetAttr(Bit8u attr);
 	void SetResultAttr(Bit8u attr);
 	bool Valid(void);
+	void ClearBlockRecsize(void);
 private:
 	bool extended;
 	PhysPt real_pt;
diff --git a/src/dos/dos_classes.cpp b/src/dos/dos_classes.cpp
index b88895ec..73c895b3 100644
--- a/src/dos/dos_classes.cpp
+++ b/src/dos/dos_classes.cpp
@@ -444,6 +444,10 @@ void DOS_FCB::SetRandom(Bit32u _random) {
 	sSave(sFCB,rndm,_random);
 }
 
+void DOS_FCB::ClearBlockRecsize(void) {
+	sSave(sFCB,cur_block,0);
+	sSave(sFCB,rec_size,0);
+}
 void DOS_FCB::FileOpen(Bit8u _fhandle) {
 	sSave(sFCB,drive,GetDrive()+1);
 	sSave(sFCB,file_handle,_fhandle);