diff --git a/lib/open_api_spex/operation_builder.ex b/lib/open_api_spex/operation_builder.ex
index 6802c286..f9c70d6d 100644
--- a/lib/open_api_spex/operation_builder.ex
+++ b/lib/open_api_spex/operation_builder.ex
@@ -108,6 +108,11 @@ defmodule OpenApiSpex.OperationBuilder do
   def build_responses(_), do: []
 
   defp status_to_code(:default), do: :default
+
+  defp status_to_code(status)
+       when status in [:"1XX", "1XX", :"2XX", "2XX", :"3XX", "3XX", :"4XX", "4XX", :"5XX", "5XX"],
+       do: status
+
   defp status_to_code(status), do: Status.code(status)
 
   def build_request_body(%{body: {description, media_type, schema}}) do
diff --git a/lib/open_api_spex/test/test_assertions.ex b/lib/open_api_spex/test/test_assertions.ex
index 6d089024..809044d6 100644
--- a/lib/open_api_spex/test/test_assertions.ex
+++ b/lib/open_api_spex/test/test_assertions.ex
@@ -156,10 +156,18 @@ defmodule OpenApiSpex.TestAssertions do
     defp validate_operation_response(conn, %Operation{operationId: operation_id} = operation, spec) do
       content_type = Utils.content_type_from_header(conn, :response)
 
+      responses = Map.get(operation, :responses, %{})
+      code_range = String.first(to_string(conn.status)) <> "XX"
+
+      response =
+        Map.get(responses, conn.status) ||
+          Map.get(responses, "#{conn.status}") ||
+          Map.get(responses, :"#{conn.status}") ||
+          Map.get(responses, code_range) ||
+          Map.get(responses, :"#{code_range}", %{})
+
       resolved_schema =
-        operation
-        |> Map.get(:responses, %{})
-        |> Map.get(conn.status, %{})
+        response
         |> Map.get(:content, %{})
         |> Map.get(content_type, %{})
         |> Map.get(:schema)
diff --git a/test/support/router.ex b/test/support/router.ex
index 217f9e70..89cc5b59 100644
--- a/test/support/router.ex
+++ b/test/support/router.ex
@@ -15,7 +15,9 @@ defmodule OpenApiSpexTest.Router do
     get "/noapi", OpenApiSpexTest.NoApiController, :noapi
     get "/noapi_with_struct", OpenApiSpexTest.NoApiControllerWithStructSpecs, :noapi
 
-    resources "/users_no_replace", OpenApiSpexTest.UserNoRepalceController, only: [:create, :index]
+    get "/response_code_ranges", OpenApiSpexTest.ResponseCodeRangesController, :index
+
+    resources "/users_no_replace", OpenApiSpexTest.UserNoReplaceController, only: [:create, :index]
 
     # Used by ParamsTest
     resources "/custom_error_users", OpenApiSpexTest.CustomErrorUserController, only: [:index]
diff --git a/test/support/string_response_codes_controller.ex b/test/support/string_response_codes_controller.ex
new file mode 100644
index 00000000..49fd8b82
--- /dev/null
+++ b/test/support/string_response_codes_controller.ex
@@ -0,0 +1,58 @@
+defmodule OpenApiSpexTest.ResponseCodeRangesController do
+  use Phoenix.Controller
+  use OpenApiSpex.ControllerSpecs
+
+  alias OpenApiSpex.Operation
+
+  defmodule GenericResponse do
+    alias OpenApiSpex.Schema
+    require OpenApiSpex
+
+    OpenApiSpex.schema(%{
+      type: :object,
+      properties: %{
+        type: %Schema{
+          type: :string,
+          enum: ["generic"]
+        }
+      }
+    })
+  end
+
+  defmodule CreatedResponse do
+    alias OpenApiSpex.Schema
+    require OpenApiSpex
+
+    OpenApiSpex.schema(%{
+      type: :object,
+      properties: %{
+        type: %Schema{
+          type: :string,
+          enum: ["created"]
+        }
+      }
+    })
+  end
+
+  operation :index,
+    operation_id: "response_code_ranges",
+    summary: "String response codes index",
+    responses: [
+      created:
+        Operation.response(
+          "Created response",
+          "application/json",
+          CreatedResponse
+        ),
+      "2XX":
+        Operation.response(
+          "Generic response",
+          "application/json",
+          GenericResponse
+        )
+    ]
+
+  def index(conn, _) do
+    json(conn, %{type: "generic"})
+  end
+end
diff --git a/test/support/user_no_replace_controller.ex b/test/support/user_no_replace_controller.ex
index b74822fe..f3d10b5a 100644
--- a/test/support/user_no_replace_controller.ex
+++ b/test/support/user_no_replace_controller.ex
@@ -1,4 +1,4 @@
-defmodule OpenApiSpexTest.UserNoRepalceController do
+defmodule OpenApiSpexTest.UserNoReplaceController do
   @moduledoc tags: ["users_no_replace"]
 
   use Phoenix.Controller
diff --git a/test/test_assertions_test.exs b/test/test_assertions_test.exs
index 9174b5e2..db896977 100644
--- a/test/test_assertions_test.exs
+++ b/test/test_assertions_test.exs
@@ -120,6 +120,18 @@ defmodule OpenApiSpex.TestAssertionsTest do
       TestAssertions.assert_operation_response(conn)
     end
 
+    test "success with a response code range" do
+      conn =
+        :get
+        |> Plug.Test.conn("/api/response_code_ranges")
+        |> Plug.Conn.put_req_header("content-type", "application/json")
+
+      conn = OpenApiSpexTest.Router.call(conn, [])
+
+      assert conn.status == 200
+      TestAssertions.assert_operation_response(conn, "response_code_ranges")
+    end
+
     test "missing operation id" do
       conn =
         :get