diff --git a/DESCRIPTION b/DESCRIPTION
index a4634f7faf889ee44e3a7bcb7cfa695174ac0a0a..6e47e6a78e54cc668e8589f8a70501fc1d869297 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: airGR
 Type: Package
 Title: Suite of GR Hydrological Models for Precipitation-Runoff Modelling
-Version: 1.4.4.22
+Version: 1.4.4.23
 Date: 2020-04-20
 Authors@R: c(
   person("Laurent", "Coron", role = c("aut", "trl"), comment = c(ORCID = "0000-0002-1503-6204")),
diff --git a/R/SeriesAggreg2.R b/R/SeriesAggreg2.R
index 52412a2da4b1ce6e9f31d433e944076ea688ab4c..a0da112431fdab5d2c4cec9414d8c6eb598616a6 100644
--- a/R/SeriesAggreg2.R
+++ b/R/SeriesAggreg2.R
@@ -36,7 +36,7 @@ SeriesAggreg2 <- function(TabSeries, Format, TimeFormat, NewTimeFormat, ConvertF
     TabSeries[[1L]] <- as.POSIXct(TabSeries[[1L]])
   }
   ## check TabSeries other columns (boolean converted to numeric)
-  apply(TabSeries[, -1L], MARGIN = 2, FUN = function(iCol) {
+  apply(TabSeries[, -1L, drop = FALSE], MARGIN = 2, FUN = function(iCol) {
     if (!is.numeric(iCol)) {
       stop("'TabSeries' columns (other than the first one) must be of numeric class")
     }