diff --git a/lib/action_mailbox/router/route.rb b/lib/action_mailbox/router/route.rb
index e9acf310b1..e123a93bb1 100644
--- a/lib/action_mailbox/router/route.rb
+++ b/lib/action_mailbox/router/route.rb
@@ -10,9 +10,9 @@ class ActionMailbox::Router::Route
   def match?(inbound_email)
     case address
     when String
-      recipients_from(inbound_email.mail).include?(address)
+      recipients_from(inbound_email.mail).any? { |recipient| address.casecmp?(recipient) }
     when Regexp
-      recipients_from(inbound_email.mail).detect { |recipient| address.match?(recipient) }
+      recipients_from(inbound_email.mail).any? { |recipient| address.match?(recipient) }
     when Proc
       address.call(inbound_email)
     else
diff --git a/test/unit/router_test.rb b/test/unit/router_test.rb
index 67a5f24c52..cc87ae6c0e 100644
--- a/test/unit/router_test.rb
+++ b/test/unit/router_test.rb
@@ -49,6 +49,15 @@ module ActionMailbox
       assert_equal inbound_email.mail, $processed_mail
     end
 
+    test "single string routing case-insensitively" do
+      @router.add_routes("first@example.com" => :first)
+
+      inbound_email = create_inbound_email_from_mail(to: "FIRST@example.com", subject: "This is a reply")
+      @router.route inbound_email
+      assert_equal "FirstMailbox", $processed_by
+      assert_equal inbound_email.mail, $processed_mail
+    end
+
     test "multiple string routes" do
       @router.add_routes("first@example.com" => :first, "second@example.com" => :second)