diff --git a/lib/iruby/display.rb b/lib/iruby/display.rb
index 3f692d5..74b966a 100644
--- a/lib/iruby/display.rb
+++ b/lib/iruby/display.rb
@@ -1,3 +1,5 @@
+require "set"
+
 module IRuby
   module Display
     class << self
@@ -50,11 +52,15 @@ def protect(mime, data)
         ascii?(mime) ? data.to_s : [data.to_s].pack('m0')
       end
 
+      # Each of the following mime types must be a text type,
+      # but mime-types library tells us it is a non-text type.
+      FORCE_TEXT_TYPES = Set[
+        "application/javascript",
+        "image/svg+xml"
+      ].freeze
+
       def ascii?(mime)
-        case mime
-        when "application/javascript"
-          # Special case for application/javascript.
-          # This needs because mime-types tells us application/javascript a non-text type.
+        if FORCE_TEXT_TYPES.include?(mime)
           true
         else
           MIME::Type.new(mime).ascii?
diff --git a/test/iruby/mime_test.rb b/test/iruby/mime_test.rb
index d7517f8..10fffa9 100644
--- a/test/iruby/mime_test.rb
+++ b/test/iruby/mime_test.rb
@@ -19,6 +19,13 @@ class IRubyTest::MimeTest < IRubyTest::TestBase
           assert_equal(data,
                        res["application/javascript"])
         end
+
+        test("image/svg+xml") do
+          data = '<svg height="30" width="100"><text x="0" y="15" fill="red">SVG</text></svg>'
+          res = IRuby::Display.display(data, mime: "image/svg+xml")
+          assert_equal(data,
+                       res["image/svg+xml"])
+        end
       end
     end
   end