diff --git a/js8call-gcc-10.patch b/js8call-gcc-10.patch
index 62c3d00..de6b70a 100644
--- a/js8call-gcc-10.patch
+++ b/js8call-gcc-10.patch
@@ -90,3 +90,16 @@ Index: js8call-2.1.1/lib/timf2.f90
    cxt(0:nh)=cx(0:nh)
  
  ! Identify frequencies with strong signals.
+Index: js8call-2.1.1/lib/wav11.f90
+===================================================================
+--- js8call-2.1.1.orig/lib/wav11.f90
++++ js8call-2.1.1/lib/wav11.f90
+@@ -14,7 +14,7 @@ subroutine wav11(d2,npts,dd)
+   jz=min(NZ12,npts)
+   x(1:jz)=d2(1:jz)
+   x(jz+1:)=0.0
+-  call four2a(x,nfft1,1,-1,0)                    !Forward FFT, r2c
++  call four2a(cx,nfft1,1,-1,0)                    !Forward FFT, r2c
+   df=12000.0/NFFT1
+   ia=5000.0/df
+   cx(ia:)=0.0