diff --git a/lib/feed_reader/formats/rss.ex b/lib/feed_reader/formats/rss.ex
index 9c9a3bf..4cd6242 100644
--- a/lib/feed_reader/formats/rss.ex
+++ b/lib/feed_reader/formats/rss.ex
@@ -7,7 +7,7 @@ defmodule FeedReader.Formats.RSS do
 
   @impl true
   def matches_prefix?(prefix) do
-    Regex.match?(~r/<rss\b[^>]*\bversion\s*=\s*(["'])2\.0\1/is, prefix)
+    Regex.match?(~r/<rss\b[^>]*\bversion\s*=\s*(["'])(?:0\.9(?:1|2)?|2\.0)\1/is, prefix)
   end
 
   @impl true
diff --git a/test/feed_reader/format_detection_test.exs b/test/feed_reader/format_detection_test.exs
index 1248845..195e7b4 100644
--- a/test/feed_reader/format_detection_test.exs
+++ b/test/feed_reader/format_detection_test.exs
@@ -5,6 +5,7 @@ defmodule FeedReader.FormatDetectionTest do
 
   test "detects RSS, Atom, and RDF from a bounded XML prefix" do
     assert FeedReader.detect_format("<?xml version='1.0'?><rss version='2.0'>") == :rss
+    assert FeedReader.detect_format("<rss version='0.91'>") == :rss
     assert FeedReader.detect_format("<feed xmlns='http://www.w3.org/2005/Atom'>") == :atom
     assert FeedReader.detect_format("<rdf:RDF xmlns:rdf='urn:rdf'>") == :rdf
     assert FeedReader.detect_format("<html><body>not a feed</body></html>") == :unknown