diff --git a/data/helpers.d/filesystem b/data/helpers.d/filesystem
index 9933563cc..27a016e63 100644
--- a/data/helpers.d/filesystem
+++ b/data/helpers.d/filesystem
@@ -70,5 +70,6 @@ ynh_bind_or_cp() {
 # usage: ynh_mkdir_tmp
 # | ret: the created directory path
 ynh_mkdir_tmp() {
+    echo "This helper is deprecated, you should use 'mktemp -d' instead." >&2
     mktemp -d
 }