diff --git a/fvn_fnlib/ze1.f90 b/fvn_fnlib/ze1.f90
index 6a2d9e3..8578133 100644
--- a/fvn_fnlib/ze1.f90
+++ b/fvn_fnlib/ze1.f90
@@ -32,7 +32,7 @@ parameter(pi=3.141592653589793D0,el=0.5772156649015328D0)
    ze1 = dcmplx(1.0D0,0.0D0)
    cr = dcmplx(1.0D0,0.0D0)
    k=0
-   do while (cdabs(cr)<=cdabs(ze1)*1.0D-15)
+   do while (cdabs(cr)>=cdabs(ze1)*1.0D-15)
      k = k+1
      cr = -cr*k*z/(k+1.0D0)**2
      ze1 = ze1+cr
@@ -50,4 +50,3 @@ parameter(pi=3.141592653589793D0,el=0.5772156649015328D0)
 !
  return
 end function
-