diff --git a/lib/xcor4.f90 b/lib/xcor4.f90
index 9e1f5a529..9e4aff59b 100644
--- a/lib/xcor4.f90
+++ b/lib/xcor4.f90
@@ -37,7 +37,7 @@ subroutine xcor4(s2,ipk,nsteps,nsym,lag1,lag2,ich,mode4,ccf,ccf0,   &
 
   ccfmax=0.
   ccfmin=0.
-  nw=nch(ich)
+  nw=nch(min(max(ich,1),7))
 
   do j=1,nsteps
      n=2*mode4