diff --git a/R/as.s2dv_cube.R b/R/as.s2dv_cube.R
index c504fbcc69ed170e96be0c510830d163712986ff..1b4c42751b1845bf90afedb6bbad4b6dd90c5156 100644
--- a/R/as.s2dv_cube.R
+++ b/R/as.s2dv_cube.R
@@ -327,13 +327,13 @@ as.s2dv_cube <- function(object, remove_attrs_coords = FALSE,
         if (!remove_attrs_coords) attr(result$coords[[dat_dim]], 'indices') <- FALSE
       }
       for (i in 2:length(names(FileSelector))) {
-        if (!is.null(lon_name_dat)) {
+        if (!(length(lon_name_dat) == 0L)) {
           if (any(result$coords[[lon_name_dat]] != as.vector(attributes(object)$Variables[[names(FileSelector)[i]]][[lon_name_dat]]))) {
             warning("'lon' values are different for different datasets. ", 
                     "Only values from the first will be used.")
           }
         }
-        if (!is.null(lat_name_dat)) {
+        if (!(length(lat_name_dat) == 0L)) {
           if (any(result$coords[[lat_name_dat]] != as.vector(attributes(object)$Variables[[names(FileSelector)[i]]][[lat_name_dat]]))) {
             warning("'lat' values are different for different datasets. ", 
                     "Only values from the first will be used.")