diff --git a/all.sas b/all.sas
index aa7d526..bcdf20d 100644
--- a/all.sas
+++ b/all.sas
@@ -4308,6 +4308,7 @@ run;
   data &out_ds;
     set &out_ds;
     length infoname infoval $60 fref $8;
+    if _n_=1 then call missing(fref);
     rc=filename(fref,filepath);
     drop rc infoname fid i close fref;
     if file_or_folder='file' then do;
diff --git a/base/mp_dirlist.sas b/base/mp_dirlist.sas
index 366ec99..4807b00 100644
--- a/base/mp_dirlist.sas
+++ b/base/mp_dirlist.sas
@@ -152,6 +152,7 @@ run;
   data &out_ds;
     set &out_ds;
     length infoname infoval $60 fref $8;
+    if _n_=1 then call missing(fref);
     rc=filename(fref,filepath);
     drop rc infoname fid i close fref;
     if file_or_folder='file' then do;