diff --git a/lib/ethers/transaction.ex b/lib/ethers/transaction.ex
index 41a328e..c82d798 100644
--- a/lib/ethers/transaction.ex
+++ b/lib/ethers/transaction.ex
@@ -195,7 +195,7 @@ defmodule Ethers.Transaction do
   @doc """
   Decodes a transaction struct values in a new map.
   """
-  @spec decode_values(t()) :: Map.t()
+  @spec decode_values(t()) :: map()
   def decode_values(%__MODULE__{} = tx) do
     tx
     |> Map.from_struct()