diff --git a/lib/fsk4hf/wspr_fsk8d.f90 b/lib/fsk4hf/wspr_fsk8d.f90
index 0dbd7f10d..923ae9289 100644
--- a/lib/fsk4hf/wspr_fsk8d.f90
+++ b/lib/fsk4hf/wspr_fsk8d.f90
@@ -121,7 +121,7 @@ program wspr_fsk8d
      pnoise=(2500.0/df1)*base                   !Noise in 2500 Hz
      xsnr=db(psig/pnoise)                       !SNR from sync tones
 
-     if(jpk.ge.0) c(0:NMAXD-1-jpk)=c(jpk:NMAX-1)
+     if(jpk.ge.0) c(0:NMAXD-1-jpk)=c(jpk:NMAXD-1)
 
      a(1)=-f0
      a(2:5)=0.