diff --git a/lib/refrepo/input_loader.rb b/lib/refrepo/input_loader.rb
index a5b5bd3a6425e0ef42b42be62731d9d3835aed2d..1975726f33b6607722087090617d77ebf7c96378 100644
--- a/lib/refrepo/input_loader.rb
+++ b/lib/refrepo/input_loader.rb
@@ -21,9 +21,15 @@ def load_yaml_file_hierarchy(directory = File.expand_path("../../input/grid5000/
         # Load YAML
         if /\.y.*ml\.erb$/.match(filename)
           # For files with .erb.yaml extensions, process the template before loading the YAML.
-          file_hash = YAML::load(ERB.new(File.read(filename)).result(binding))
+          file_hash = YAML::load(
+            ERB.new(File.read(filename)).result(binding),
+            permitted_classes: [Date, Time]
+          )
         else
-          file_hash = YAML::load_file(filename)
+          file_hash = YAML::load_file(
+            filename,
+            permitted_classes: [Date, Time]
+          )
         end
       if not file_hash
         raise StandardError.new("loaded hash is empty")