diff --git a/.dialyzer_ignore b/.dialyzer_ignore
new file mode 100644
index 0000000..38b22ca
--- /dev/null
+++ b/.dialyzer_ignore
@@ -0,0 +1 @@
+lib/cream/continuum.ex:42: Guard test _@1::'true' =:= 'false' can never succeed
diff --git a/lib/cream/cluster.ex b/lib/cream/cluster.ex
index 82c4185..8bd6717 100644
--- a/lib/cream/cluster.ex
+++ b/lib/cream/cluster.ex
@@ -53,10 +53,15 @@ defmodule Cream.Cluster do
   """
   @type item :: {key, value}
 
+  @typedoc """
+  Multiple items as a map.
+  """
+  @type items_map :: %{required(key) => value}
+
   @typedoc """
   Multiple items as a list of tuples or a map.
   """
-  @type items :: [item] | [%{required(key) => value}]
+  @type items :: [item] | items_map
 
   @typedoc """
   Reason associated with an error.
@@ -286,8 +291,9 @@ defmodule Cream.Cluster do
   set(cluster, %{k1 => v1, k2 => v2}, ttl: 300)
   ```
   """
-  @spec set(t, item | items, Keyword.t) :: :ok | {:error, reason}
-  def set(cluster, item_or_items, opts \\ [])
+ @spec set(t, item, Keyword.t()) :: :ok | {:error, reason}
+ @spec set(t, items, Keyword.t()) :: %{required(key) => :ok | {:error, reason}}
+ def set(cluster, item_or_items, opts \\ [])
 
   def set(cluster, items, opts) when is_list(items) or is_map(items) do
     with_worker cluster, fn worker ->
@@ -310,8 +316,8 @@ defmodule Cream.Cluster do
   %{"foo" => "bar", "one" => "one"} = get(pid, ["foo", "bar"])
   ```
   """
-  @spec get(t, key, Keyword.t) :: value
-  @spec get(t, keys, Keyword.t) :: items
+  @spec get(t, key, Keyword.t) :: value | nil
+  @spec get(t, keys, Keyword.t) :: items_map
   def get(cluster, key_or_keys, opts \\ [])
 
   def get(cluster, key, opts) when is_binary(key) do
diff --git a/lib/cream/cluster/worker.ex b/lib/cream/cluster/worker.ex
index bbcc44a..fd661bc 100644
--- a/lib/cream/cluster/worker.ex
+++ b/lib/cream/cluster/worker.ex
@@ -28,7 +28,12 @@ defmodule Cream.Cluster.Worker do
     end
 
     reply = Enum.reduce pairs_by_conn, %{}, fn {conn, pairs}, acc ->
-      {:ok, responses} = Memcache.multi_set(conn, pairs, options)
+      responses = case Memcache.multi_set(conn, pairs, options) do
+        {:ok, results} -> results
+        {:error, reason} when is_atom(reason) -> Enum.map(pairs, fn _ ->
+          {:error, Atom.to_string(reason)}
+        end)
+      end
 
       Enum.zip(pairs, responses)
         |> Enum.reduce(acc, fn {pair, status}, acc ->
diff --git a/mix.exs b/mix.exs
index fcdff1c..89f3e05 100644
--- a/mix.exs
+++ b/mix.exs
@@ -24,7 +24,8 @@ defmodule Cream.Mixfile do
          "README.md": [title: "README"],
          "CHANGELOG.md": [title: "CHANGELOG"]
        ]
-     ]
+     ],
+     dialyzer: [ignore_warnings: ".dialyzer_ignore"]
    ]
   end