diff --git a/lib/kubernetes-deploy/kubernetes_resource/custom_resource_definition.rb b/lib/kubernetes-deploy/kubernetes_resource/custom_resource_definition.rb
index bfa7a6699..125e07f16 100644
--- a/lib/kubernetes-deploy/kubernetes_resource/custom_resource_definition.rb
+++ b/lib/kubernetes-deploy/kubernetes_resource/custom_resource_definition.rb
@@ -97,7 +97,9 @@ def validate_params(params)
       params[:failure_queries].each do |query|
         JsonPath.new(query[:path])
         JsonPath.new(query[:error_msg_path]) if query[:error_msg_path]
-        raise RuntimeError if query[:custom_error_msg] && !query[:custom_error_msg].is_a?(String)
+        if query[:custom_error_msg] && !query[:custom_error_msg].is_a?(String)
+          raise RuntimeError, "custom_error_msg must be a string, but found #{query[:custom_error_msg]}"
+        end
       end
     rescue RuntimeError => e
       raise FatalDeploymentError, "error parsing JsonPath expression for custom resource params: #{e.message}"