diff --git a/lib/ft4/ft4_decode.f90 b/lib/ft4/ft4_decode.f90
index 6fc0059f3..29427ffb9 100644
--- a/lib/ft4/ft4_decode.f90
+++ b/lib/ft4/ft4_decode.f90
@@ -1,4 +1,5 @@
-subroutine ft4_decode(cdatetime0,nfqso,iwave,ndecodes,mycall,hiscall,nrx,line)
+subroutine ft4_decode(cdatetime0,nfa,nfb,nfqso,iwave,ndecodes,mycall,    &
+     hiscall,nrx,line)
 
    use packjt77
    include 'ft4_params.f90'
@@ -66,12 +67,11 @@ subroutine ft4_decode(cdatetime0,nfqso,iwave,ndecodes,mycall,hiscall,nrx,line)
    syncmin=1.2
    maxcand=100
 
-! These are temporary.  Correct values should be passed in as arguments.
+! ### This is temporary.  Correct directory should be passed in as an argument.
    data_dir="."
-   fMHz=7.074
-   fa=400.0
-   fb=3000.0
 
+   fa=nfa
+   fb=nfb
    call getcandidates4(iwave,fa,fb,syncmin,nfqso,maxcand,savg,candidate,   &
         ncand,sbase)
 
diff --git a/lib/ft4/ft4d.f90 b/lib/ft4/ft4d.f90
index 1f4dccd59..c0bd15270 100644
--- a/lib/ft4/ft4d.f90
+++ b/lib/ft4/ft4d.f90
@@ -43,6 +43,8 @@ program ft4d
       iarg=iarg+2
    endif
    ncoh=1
+   nfa=200
+   nfb=3000
 
    do ifile=iarg,nargs
       call getarg(ifile,infile)
@@ -54,7 +56,8 @@ program ft4d
       cdatetime='      '//datetime
       close(10)
 
-      call ft4_decode(cdatetime,nfqso,iwave,ndecodes,mycall,hiscall,nrx,line)
+      call ft4_decode(cdatetime,nfa,nfb,nfqso,iwave,ndecodes,mycall,    &
+           hiscall,nrx,line)
       if(ndecodes.ge.1) write(*,'(a61)') line
    enddo !files
 
diff --git a/lib/ft4/getcandidates4.f90 b/lib/ft4/getcandidates4.f90
index 436ce59d1..402116a27 100644
--- a/lib/ft4/getcandidates4.f90
+++ b/lib/ft4/getcandidates4.f90
@@ -45,7 +45,9 @@ subroutine getcandidates4(id,fa,fb,syncmin,nfqso,maxcand,savg,candidate,   &
     savsm(i)=sum(savg(i-7:i+7))/15.
   enddo
   nfa=fa/df
+  if(nfa.lt.1) nfa=1
   nfb=fb/df
+  if(nfb.gt.nint(5000.0/df)) nfb=nint(5000.0/df)
   np=nfb-nfa+1
   indx=0
   call indexx(savsm(nfa:nfb),np,indx)
diff --git a/widgets/mainwindow.cpp b/widgets/mainwindow.cpp
index b6004ca9c..e63f57124 100644
--- a/widgets/mainwindow.cpp
+++ b/widgets/mainwindow.cpp
@@ -163,8 +163,8 @@ extern "C" {
 
   void chkcall_(char* w, char* basc_call, bool cok, int len1, int len2);
 
-  void ft4_decode_(char* cdatetime, int* nfqso, short int id[], int* ndecodes,
-                   char* mycall6, char* hiscall6, int* nrx, char* line,
+  void ft4_decode_(char* cdatetime, int* nfa, int* nfb, int* nfqso, short int id[],
+                   int* ndecodes, char* mycall6, char* hiscall6, int* nrx, char* line,
                    int len1, int len2, int len3, int len4);
 }
 
@@ -8652,8 +8652,10 @@ void MainWindow::ft4Data(int k)
   int nfqso=1500;
   int ndecodes=0;
   int nrx=-1;
-  ft4_decode_(cdatetime,&nfqso,id,&ndecodes,mycall6,hiscall6,&nrx,&line[0],
-      17,6,6,61);
+  int nfa=m_wideGraph->nStartFreq();
+  int nfb=m_wideGraph->Fmax();
+  ft4_decode_(cdatetime,&nfa,&nfb,&nfqso,id,&ndecodes,mycall6,hiscall6,
+              &nrx,&line[0],17,6,6,61);
   line[60]=0;
   if(ndecodes>0) {
     QString sline{QString::fromLatin1(line)};