diff --git a/devops-service/lib/executors/stack_executor/chef_node_name_builder.rb b/devops-service/lib/executors/stack_executor/chef_node_name_builder.rb
index 2e85488..a774a88 100644
--- a/devops-service/lib/executors/stack_executor/chef_node_name_builder.rb
+++ b/devops-service/lib/executors/stack_executor/chef_node_name_builder.rb
@@ -65,7 +65,7 @@ class Devops::Executor::StackExecutor
     def increment_variable_value(variable_name)
       used_values = @already_used_incrementers_values[variable_name] || []
       prev_value = used_values.sort.detect {|t| !used_values.include?(t+1)}
-      @incrementers_values[variable_name] = (prev_value || 0) + 1
+      @incrementers_values[variable_name] = prev_value.to_i + 1
     end
   end
 end
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