diff --git a/utils/chem/chem_diagb.h b/utils/chem/chem_diagb.h
index d5456d3d6..a5a1ee36a 100644
--- a/utils/chem/chem_diagb.h
+++ b/utils/chem/chem_diagb.h
@@ -189,7 +189,7 @@ namespace gdasapp {
             auto stdDevBkg = atlas::array::make_view<double, 2>(bkgErrFs[var]);
 
             // Loops through nodes and levels
-            for (atlas::idx_t level = 0; level <= xbFs[var].shape(1); ++level) {
+            for (atlas::idx_t level = 0; level < xbFs[var].shape(1); ++level) {
               for (atlas::idx_t jnode = 0; jnode < xbFs[var].shape(0); ++jnode) {
                 std::vector<double> local;
                 auto neighbors = get_neighbors_of_node(jnode);