diff --git a/DESCRIPTION b/DESCRIPTION
index 71a1f82057939411545d2c4d6cfced9a6f1f8e17..96f93165adcefcc6cd4898b977c6b5082535df8a 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: airGR
 Type: Package
 Title: Suite of GR Hydrological Models for Precipitation-Runoff Modelling
-Version: 1.4.4.10
+Version: 1.4.4.11
 Date: 2020-04-09
 Authors@R: c(
   person("Laurent", "Coron", role = c("aut", "trl"), comment = c(ORCID = "0000-0002-1503-6204")),
diff --git a/NEWS.md b/NEWS.md
index 7c12087c1d59853f8a4865340af536eb0df7a733..6709e620c1c986820d4f5465177cbde01ec64813 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,7 +4,7 @@
 
 
 
-### 1.4.4.10 Release Notes (2020-04-09)
+### 1.4.4.11 Release Notes (2020-04-09)
 
 #### New features
 
diff --git a/R/SeriesAggreg2.R b/R/SeriesAggreg2.R
index 32d0554e9642822b56395c84e37f9d26466dffc3..b39f8874d379f8af094136f415029323c0b98eef 100644
--- a/R/SeriesAggreg2.R
+++ b/R/SeriesAggreg2.R
@@ -27,6 +27,22 @@ SeriesAggreg2 <- function(TabSeries,  Format, ConvertFun,
   listFormat <- c("%Y%m%d", "%Y%m", "%Y", "%m", "%d")
   Format <- gsub(pattern = "[[:punct:]]+", replacement = "%", Format)
   Format <- match.arg(Format, choices = listFormat)
+  ## check ConvertFun
+  if (!is.vector(ConvertFun)) {
+    stop("'ConvertFun' must be a vector of character")
+  }
+  if (!is.character(ConvertFun)) {
+    stop("'ConvertFun' must be a vector of character")
+  }
+  if (length(ConvertFun) != (ncol(TabSeries) - 1)) {
+    stop(
+      sprintf("'ConvertFun' must be of length %i (ncol(TabSeries)-1)", ncol(TabSeries) - 1)
+    )
+  }
+  if (!all(ConvertFun %in% c("sum", "mean"))) {
+    stop("'ConvertFun' should be one of 'sum' or 'mean'")
+  }
+  
   
   sp <- sprintf("%02.f", YearFirstMonth)