diff --git a/.dialyzer_ignore_warnings b/.dialyzer_ignore_warnings
new file mode 100644
index 0000000..1beb3b1
--- /dev/null
+++ b/.dialyzer_ignore_warnings
@@ -0,0 +1,2 @@
+:0: Unknown function persistent_term:get/2
+:0: Unknown function persistent_term:put/2
diff --git a/lib/cldr/backend/relative.ex b/lib/cldr/backend/relative.ex
index 56dcda1..ae4b980 100644
--- a/lib/cldr/backend/relative.ex
+++ b/lib/cldr/backend/relative.ex
@@ -127,7 +127,7 @@ defmodule Cldr.DateTime.Relative.Backend do
 
         """
 
-        @spec to_string(integer | float | Date.t() | DateTime.t(), Keyword.t()) ::
+        @spec to_string(number | map(), Keyword.t()) ::
                 {:ok, String.t()} | {:error, {module, String.t()}}
 
         def to_string(time, options \\ []) do
@@ -164,7 +164,7 @@ defmodule Cldr.DateTime.Relative.Backend do
         See `to_string/2`
 
         """
-        @spec to_string!(number, Keyword.t()) :: String.t()
+        @spec to_string!(number | map(), Keyword.t()) :: String.t()
         def to_string!(time, options \\ []) do
           Cldr.DateTime.Relative.to_string!(time, unquote(backend), options)
         end
diff --git a/mix.exs b/mix.exs
index 970edf1..cf4c357 100644
--- a/mix.exs
+++ b/mix.exs
@@ -16,7 +16,10 @@ defmodule CldrDatesTimes.Mixfile do
       start_permanent: Mix.env() == :prod,
       deps: deps(),
       compilers: Mix.compilers(),
-      elixirc_paths: elixirc_paths(Mix.env())
+      elixirc_paths: elixirc_paths(Mix.env()),
+      dialyzer: [
+        ignore_warnings: ".dialyzer_ignore_warnings"
+      ]
     ]
   end