diff --git a/app/models/report.rb b/app/models/report.rb
index 6eb79b54b0de..3f66634177fa 100644
--- a/app/models/report.rb
+++ b/app/models/report.rb
@@ -62,7 +62,7 @@ def self.inherited(child)
   # extracts serialized metrics and keep them as a hash_with_indifferent_access
   def metrics
     return {} if self[:metrics].nil?
-    YAML.safe_load(read_metrics, permitted_classes: [ActiveSupport::HashWithIndifferentAccess]).with_indifferent_access
+    YAML.safe_load(read_metrics, permitted_classes: [ActiveSupport::HashWithIndifferentAccess, Symbol]).with_indifferent_access
   end
 
   # serialize metrics as YAML