diff --git a/lib/savec2.f90 b/lib/savec2.f90
index 55b4ff476..d1cafec92 100644
--- a/lib/savec2.f90
+++ b/lib/savec2.f90
@@ -1,4 +1,4 @@
-subroutine savec2(c2name,ntrseconds,f0m1500)
+integer function savec2(c2name,ntrseconds,f0m1500)
 
 ! Array c0() has complex samples at 1500 Hz sample rate.
 ! WSPR-2:  downsample by 1/4 to produce c2, centered at 1500 Hz
@@ -46,9 +46,10 @@ subroutine savec2(c2name,ntrseconds,f0m1500)
 ! Write complex time-domain data to disk.
   i1=index(c2name,'.c2')
   outfile=c2name(i1-11:i1+2)
-  open(18,file=c2name,status='unknown',access='stream')
-  write(18) outfile,ntrminutes,f0m1500,c2(0:45000-1)
-  close(18)
-
-  return
-end subroutine savec2
+  open(18,file=c2name,status='unknown',access='stream', iostat=ioerr)
+  if (ioerr.ne.0) then
+     write(18) outfile,ntrminutes,f0m1500,c2(0:45000-1)
+     close(18)
+  endif
+  savec2 = ioerr
+end function savec2
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 4a2442839..54a96fb6c 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -102,7 +102,7 @@ extern "C" {
   int ptt_(int nport, int ntx, int* iptt, int* nopen);
 
   void wspr_downsample_(short int d2[], int* k);
-  void savec2_(char* fname, int* TR_seconds, double* dial_freq, int len1);
+  int savec2_(char* fname, int* TR_seconds, double* dial_freq, int len1);
 
   void avecho_( short id2[], int* dop, int* nfrit, int* nqual, float* f1,
                 float* level, float* sigdb, float* snr, float* dfreq,
@@ -1177,7 +1177,8 @@ void MainWindow::dataSink(qint64 frames)
         int nsec=120;
         int nbfo=1500;
         double f0m1500=m_freqNominal/1000000.0 + nbfo - 1500;
-        savec2_(c2name,&nsec,&f0m1500,len1);
+        int err = savec2_(c2name,&nsec,&f0m1500,len1);
+        if (err!=0) MessageBox::warning_message (this, tr ("Error saving c2 file"), c2name);
       }
     }