diff --git a/lib/qra64a.f90 b/lib/qra64a.f90
index d141e06d6..0892e04ae 100644
--- a/lib/qra64a.f90
+++ b/lib/qra64a.f90
@@ -105,7 +105,7 @@ subroutine qra64a(dd0,nutc,nf1,nf2,nfqso,ntol,mycall_12,hiscall_12,   &
 !  write(*,5001) dtx,nint(f0),0,snr1
 !5001 format(f6.3,2i6,f7.1)
   maxf1=10
-  call sync64(dd0,nf1,nf2,nfqso,ntol,maxf1,dtx,f0,kpk,snr,s3a)
+!  call sync64(dd0,nf1,nf2,nfqso,ntol,maxf1,dtx,f0,kpk,snr,s3a)
 !  write(*,5001) dtx,nint(f0),kpk,snr
 
   mycall=mycall_12(1:6)                     !### May need fixing ###
diff --git a/lib/sync64.f90 b/lib/sync64.f90
index 666bd51c6..6c2c5b974 100644
--- a/lib/sync64.f90
+++ b/lib/sync64.f90
@@ -104,8 +104,8 @@ subroutine sync64(dd,nf1,nf2,nfqso,ntol,maxf1,dtx,f0,kpk,snrdb,s3a)
            endif
         enddo
      enddo
-     ja=jpk-2*jstep
-     jb=jpk+2*jstep
+     ja=max(0,jpk-2*jstep)
+     jb=min(336000-NSPC,jpk+2*jstep)
      jstep=10
 !     ka=kpk
 !     kb=kpk