diff --git a/Dockerfile b/Dockerfile
index 3e370142..00c8c9f2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -68,6 +68,7 @@ RUN rm -rf ./node_modules ./tmp/cache ./.git ./test ./doc
 USER root
 RUN apk add --no-cache findutils
 RUN find /home/app/checkout/vendor/ruby/2.7.0 -maxdepth 3 -type d -name test -o -name spec -o -name rubocop | xargs -r rm -rf
+RUN cd /home/app/checkout/vendor/ruby/2.7.0/gems/prometheus_exporter-0.5.3 && patch -Np 0 -i /home/app/checkout/prom.patch
 
 # Contenedor final
 FROM sutty/monit:latest
diff --git a/prom.patch b/prom.patch
new file mode 100644
index 00000000..27c1d4a0
--- /dev/null
+++ b/prom.patch
@@ -0,0 +1,11 @@
+--- lib/prometheus_exporter/instrumentation/active_record.rb.orig	2020-10-05 19:06:08.912325451 -0300
++++ lib/prometheus_exporter/instrumentation/active_record.rb	2020-10-05 19:06:12.229036702 -0300
+@@ -69,7 +69,7 @@
+ 
+         labels_from_config = pool.spec.config
+           .select { |k, v| @config_labels.include? k }
+-          .map { |k, v| [k.to_s.prepend("dbconfig_"), v] }
++          .map { |k, v| [k.to_s.dup.prepend("dbconfig_"), v] }
+ 
+         labels = @metric_labels.merge(pool_name: pool.spec.name).merge(Hash[labels_from_config])
+