diff --git a/DESCRIPTION b/DESCRIPTION
index 4c0c69c..ba96d86 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -35,7 +35,7 @@ Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.3.1
 VignetteBuilder: knitr
 Depends: 
-    R (>= 4.0)
+    R (>= 4.1.0)
 Imports: 
     dplyr,
     jsonlite,
diff --git a/README.Rmd b/README.Rmd
index 29abbf8..c060fa2 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -82,6 +82,7 @@ Then you can attach the package `forcis`:
 library("forcis")
 ```
 
+**N.B.** The `forcis` package requires at least the version of **4.1.0 of R**. Please update R if you are using an older version.
 
 
 ## Get started
diff --git a/README.md b/README.md
index a140ae6..604130a 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,9 @@ Then you can attach the package `forcis`:
 library("forcis")
 ```
 
+**N.B.** The `forcis` package requires at least the version of **4.1.0
+of R**. Please update R if you are using an older version.
+
 ## Get started
 
 For an overview of the main features of `forcis`, please read the [Get