diff --git a/lib/q65_sync.f90 b/lib/q65_sync.f90
index 741436b55..e0459edc5 100644
--- a/lib/q65_sync.f90
+++ b/lib/q65_sync.f90
@@ -144,7 +144,7 @@ subroutine q65_sync(nutc,iwave,nmax,mode_q65,codewords,ncw,nsps,nfqso,ntol, &
            j=j0 + NSTEP*(k-1) + 1 + lag
            if(j.ge.1 .and. j.le.jz) then
               do i=-ia2,ia2
-                 ii=i0+mode_q65*itone(k)+i
+                 ii=i0+mode_q65*(itone(k)+1)+i
                  if(ii.ge.1 .and. ii.le.iz) ccf(i,lag)=ccf(i,lag) + s1(ii,j)
               enddo
            endif
@@ -156,7 +156,7 @@ subroutine q65_sync(nutc,iwave,nmax,mode_q65,codewords,ncw,nsps,nfqso,ntol, &
         ijpk=maxloc(ccf(-ia:ia,:))
         ipk=ijpk(1)-ia-1
         jpk=ijpk(2)-53-1     
-        f0=nfqso + (ipk-mode_q65)*df
+        f0=nfqso + ipk*df
         xdt=jpk*dtstep
         imsg_best=imsg
         ccf1=ccf(:,jpk)
@@ -232,7 +232,6 @@ subroutine q65_sync(nutc,iwave,nmax,mode_q65,codewords,ncw,nsps,nfqso,ntol, &
   ijpk=maxloc(ccf(-ia:ia,:))
   ipk=ijpk(1)-ia-1
   jpk=ijpk(2)-53-1
-
   f0=nfqso + ipk*df
   xdt=jpk*dtstep
   sq=0.