diff --git a/lib/fsk4hf/gen_wspr4wave.f90 b/lib/fsk4hf/gen_wspr4wave.f90
index b19f57bf3..15b266f51 100644
--- a/lib/fsk4hf/gen_wspr4wave.f90
+++ b/lib/fsk4hf/gen_wspr4wave.f90
@@ -7,12 +7,13 @@ subroutine gen_wspr4wave(itone,nsym,nsps,fsample,f0,cwave,wave,icmplx,nwave)
   integer itone(nsym)
   logical first
   data first/.true./
-  save pulse,first,twopi,dt,hmod
+  save pulse,first,twopi,dt,hmod,tsym
 
   if(first) then
      allocate( pulse(3*nsps*fsample) )
      twopi=8.0*atan(1.0)
      dt=1.0/fsample
+     tsym=nsps/fsample
      hmod=1.0
 ! Compute the smoothed frequency-deviation pulse
      do i=1,3*nsps
@@ -35,7 +36,7 @@ subroutine gen_wspr4wave(itone,nsym,nsps,fsample,f0,cwave,wave,icmplx,nwave)
 
 ! Calculate and insert the audio waveform
   phi=0.0
-  dphi = dphi + twopi*f0*dt                          !Shift frequency up by f0
+  dphi = dphi + twopi*(f0-1.5/tsym)*dt                          !Shift frequency up by f0
   wave=0.
   if(icmplx.eq.1) cwave=0.
   k=0