diff --git a/sources/user_problem.F90 b/sources/user_problem.F90
index df938a4..12d29fc 100644
--- a/sources/user_problem.F90
+++ b/sources/user_problem.F90
@@ -1037,7 +1037,7 @@ module user_problem
     do while(associated(pdata))
       pmeta => pdata%meta
 
-      if (pmeta%xmin <= 0.0d+00 .and. pmeta%xmax >= 0.0d+00) then
+      if (pmeta%xmin <= 0.0d+00 .and. 0.0d+00 < pmeta%xmax) then
 
         dh(1) = adx(pmeta%level)
         dh(2) = ady(pmeta%level)
@@ -1046,11 +1046,11 @@ module user_problem
         x(:) = pmeta%xmin + ax(pmeta%level,:)
 
         i = nb
-        do while(abs(x(i)) > dh(1) .and. i <= ne)
+        do while(abs(x(i)) > dh(1) .and. i < ne)
           i = i + 1
         end do
 
-        if (nb < i .and. i <= ne) then
+        if (nb <= i .and. i < ne) then
 
           dyz = ady(pmeta%level) * adz(pmeta%level)