diff --git a/VERSION b/VERSION
index cd57a8b9..399088bf 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.1.5
+2.1.6
diff --git a/lib/supavisor/monitoring/prom_ex.ex b/lib/supavisor/monitoring/prom_ex.ex
index 8a7c50ca..700dffc1 100644
--- a/lib/supavisor/monitoring/prom_ex.ex
+++ b/lib/supavisor/monitoring/prom_ex.ex
@@ -58,7 +58,7 @@ defmodule Supavisor.Monitoring.PromEx do
     end
   end
 
-  @spec get_metrics() :: String.t()
+  @spec get_metrics() :: iodata()
   def get_metrics do
     metrics_tags =
       case Application.fetch_env(:supavisor, :metrics_tags) do
@@ -71,7 +71,7 @@ defmodule Supavisor.Monitoring.PromEx do
     metrics =
       PromEx.get_metrics(__MODULE__)
       |> String.split("\n")
-      |> Enum.map_join("\n", &parse_and_add_tags(&1, def_tags))
+      |> Enum.map(&parse_and_add_tags(&1, def_tags))
 
     Supavisor.Monitoring.PromEx.ETSCronFlusher
     |> PromEx.ETSCronFlusher.defer_ets_flush()
@@ -81,7 +81,7 @@ defmodule Supavisor.Monitoring.PromEx do
 
   @spec do_cache_tenants_metrics() :: list
   def do_cache_tenants_metrics do
-    metrics = get_metrics() |> String.split("\n")
+    metrics = get_metrics() |> IO.iodata_to_binary() |> String.split("\n")
 
     pools =
       Registry.select(Supavisor.Registry.TenantClients, [{{:"$1", :_, :_}, [], [:"$1"]}])
@@ -109,7 +109,7 @@ defmodule Supavisor.Monitoring.PromEx do
     end
   end
 
-  @spec parse_and_add_tags(String.t(), String.t()) :: String.t()
+  @spec parse_and_add_tags(String.t(), String.t()) :: iodata()
   defp parse_and_add_tags(line, def_tags) do
     case Regex.run(~r/(?!\#)^(\w+)(?:{(.*?)})?\s*(.+)$/, line) do
       nil ->
@@ -122,10 +122,10 @@ defmodule Supavisor.Monitoring.PromEx do
           if tags == "" do
             def_tags
           else
-            "#{tags},#{def_tags}"
+            [tags, ",", def_tags]
           end
 
-        "#{key}{#{tags}} #{value}"
+        [key, "{", tags, "}", value, "\n"]
     end
   end
 
diff --git a/lib/supavisor_web/controllers/metrics_controller.ex b/lib/supavisor_web/controllers/metrics_controller.ex
index cd34d67a..2b9f92c6 100644
--- a/lib/supavisor_web/controllers/metrics_controller.ex
+++ b/lib/supavisor_web/controllers/metrics_controller.ex
@@ -56,6 +56,6 @@ defmodule SupavisorWeb.MetricsController do
   end
 
   def merge_node_metrics({_, {_node, metrics}}, acc) do
-    [metrics <> "\n" | acc]
+    [metrics, "\n" | acc]
   end
 end