diff --git a/lib/trinity/sim_file.ex b/lib/trinity/sim_file.ex
index 310a427..301b3b5 100644
--- a/lib/trinity/sim_file.ex
+++ b/lib/trinity/sim_file.ex
@@ -21,6 +21,14 @@ defmodule Trinity.SimFile do
     end
   end
 
+  @spec close(file_descriptor) :: :ok | {:error, posix | :badarg | :terminated}
+  def close(fd) do
+    case get_sim() do
+      nil -> File.close(fd)
+      _sim -> sim_close(fd)
+    end
+  end
+
   @spec pread(file_descriptor, non_neg_integer, non_neg_integer) :: {:ok, binary} | :eof | {:error, posix}
   def pread(fd, loc, bytes) do
     case get_sim() do
@@ -78,6 +86,10 @@ defmodule Trinity.SimFile do
     end
   end
 
+  defp sim_close(_fd) do
+    :ok
+  end
+
   defp get_or_create_fd(file_paths, node, path) do
     case get_path(file_paths, node, path) do
       fd when is_integer(fd) -> {:ok, fd}