diff --git a/lib/protobuf/protoc/generator/message.ex b/lib/protobuf/protoc/generator/message.ex
index bacc05e3..032ef543 100644
--- a/lib/protobuf/protoc/generator/message.ex
+++ b/lib/protobuf/protoc/generator/message.ex
@@ -370,7 +370,12 @@ defmodule Protobuf.Protoc.Generator.Message do
           [Map.from_struct(opt) | acc]
       end
     end)
-    |> inspect(limit: :infinity)
+    |> case do
+      [] ->
+        nil
+      opts ->
+        inspect(opts, limit: :infinity)
+    end
   end
 
   defp cal_message_options(_opts) do
diff --git a/test/protobuf/protoc/proto/extension3.proto b/test/protobuf/protoc/proto/extension3.proto
index 9f685705..62110818 100644
--- a/test/protobuf/protoc/proto/extension3.proto
+++ b/test/protobuf/protoc/proto/extension3.proto
@@ -10,3 +10,7 @@ message MyEventMessage {
   option (brex.events.extension.message).is_event = true;
   google.protobuf.DoubleValue f1 = 1 [(brex.elixirpb.field).extype="float"];
 }
+
+message MyNonEventMessage {
+  map<string, string> args = 1;
+}
diff --git a/test/protobuf/protoc/proto_gen/extension3.pb.ex b/test/protobuf/protoc/proto_gen/extension3.pb.ex
index eb24c9ee..4e31c811 100644
--- a/test/protobuf/protoc/proto_gen/extension3.pb.ex
+++ b/test/protobuf/protoc/proto_gen/extension3.pb.ex
@@ -19,3 +19,39 @@ defmodule Ext.MyEventMessage do
 
   field :f1, 1, type: Google.Protobuf.DoubleValue, options: [extype: "float"]
 end
+
+defmodule Ext.MyNonEventMessage.ArgsEntry do
+  @moduledoc false
+  use Protobuf, custom_field_options?: true, map: true, syntax: :proto3
+
+  @type t :: %__MODULE__{
+          key: String.t(),
+          value: String.t()
+        }
+
+  defstruct [:key, :value]
+
+  def full_name do
+    "ext.MyNonEventMessage.ArgsEntry"
+  end
+
+  field :key, 1, type: :string
+  field :value, 2, type: :string
+end
+
+defmodule Ext.MyNonEventMessage do
+  @moduledoc false
+  use Protobuf, custom_field_options?: true, syntax: :proto3
+
+  @type t :: %__MODULE__{
+          args: %{String.t() => String.t()}
+        }
+
+  defstruct [:args]
+
+  def full_name do
+    "ext.MyNonEventMessage"
+  end
+
+  field :args, 1, repeated: true, type: Ext.MyNonEventMessage.ArgsEntry, map: true
+end