diff --git a/lib/websocket/extensions/parser.rb b/lib/websocket/extensions/parser.rb
index f8d8891..fab504c 100644
--- a/lib/websocket/extensions/parser.rb
+++ b/lib/websocket/extensions/parser.rb
@@ -43,7 +43,8 @@ def self.parse_header(header)
             end
 
             if offer.has_key?(key)
-              offer[key] = [*offer[key]] + [data]
+              offer[key] = [offer[key]] unless offer[key].is_a?(Array)
+              offer[key].push(data)
             else
               offer[key] = data
             end
diff --git a/spec/websocket/extensions/parser_spec.rb b/spec/websocket/extensions/parser_spec.rb
index 7458210..9a6d488 100644
--- a/spec/websocket/extensions/parser_spec.rb
+++ b/spec/websocket/extensions/parser_spec.rb
@@ -67,6 +67,12 @@ def parse(string)
       ]
     end
 
+    it "preserves more than two duplicate params in order" do
+      expect(parse "a; b=1; b=2; b=3").to eq [
+        { :name => "a", :params => { "b" => [1, 2, 3] } }
+      ]
+    end
+
     it "parses multiple complex offers" do
       expect(parse 'a; b=1, c, b; d, c; e="hi, there"; e, a; b').to eq [
         { :name => "a", :params => { "b" => 1 } },