diff --git a/lib/httparty/cookie_hash.rb b/lib/httparty/cookie_hash.rb
index 7bd65b3..29176dc 100644
--- a/lib/httparty/cookie_hash.rb
+++ b/lib/httparty/cookie_hash.rb
@@ -1,5 +1,5 @@
 class HTTParty::CookieHash < Hash #:nodoc:
-  CLIENT_COOKIES = %w(path expires domain path secure httponly)
+  CLIENT_COOKIES = %w(path expires domain path secure httponly samesite)
 
   def add_cookies(value)
     case value
diff --git a/spec/httparty/cookie_hash_spec.rb b/spec/httparty/cookie_hash_spec.rb
index 40db9b1..2309265 100644
--- a/spec/httparty/cookie_hash_spec.rb
+++ b/spec/httparty/cookie_hash_spec.rb
@@ -79,6 +79,12 @@ RSpec.describe HTTParty::CookieHash do
       expect(@s).not_to match(/path=\//)
     end
 
+    it "should not include SameSite attribute" do
+      @cookie_hash.add_cookies(samesite: "Strict")
+      @s = @cookie_hash.to_cookie_string
+      expect(@s).not_to match(/samesite=Strict/)
+    end
+
     it "should not include client side only cookies even when attributes use camal case" do
       @cookie_hash.add_cookies(Path: "/")
       @s = @cookie_hash.to_cookie_string