diff --git a/lib/ft8/subtractft8.f90 b/lib/ft8/subtractft8.f90
index 7d6084875..40657e7e7 100644
--- a/lib/ft8/subtractft8.f90
+++ b/lib/ft8/subtractft8.f90
@@ -8,7 +8,7 @@ subroutine subtractft8(dd0,itone,f0,dt,lrefinedt)
 ! Subtract         : dd(t)    = dd(t) - 2*REAL{cref*cfilt}
 
   parameter (NMAX=15*12000,NFRAME=1920*79)
-  parameter (NFFT=NMAX,NFILT=6500)
+  parameter (NFFT=NMAX,NFILT=4000)
   real dd(NMAX),dd0(NMAX)
   real window(-NFILT/2:NFILT/2)
   real x(NFFT+2)